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80 Cards in this Set

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1. Drivers must fill out a vehicle inspection report form:


A. if they are owner-operators


B. if the vehicle they take out is different than the one they had the day before


C. on the first vehicle they take out each day


D. on each vehicle they operate during the day



The correct answer is D. Every vehicle must be inspected prior to being driven on the road. Each driver is responsible for every vehicle they drive, whether or not the vehicle has been previously inspected that day by another driver. In addition to assuring that the vehicle is safe, drivers are required to review the last vehicle inspection report. If any defects noted by the previous driver are repaired, both the technician and the new driver must sign off on the work before the vehicle can be dispatched. If the problem noted did not require repair, that too should be noted.

2. When Winterizing a truck, which of the following procedures comes first?


A. adding antifreeze


B. cleaning the cooling system


C. testing the freeze point of the coolant


D. send a coolant sample to an approved laboratory

The correct answer is C. When Winterizing a truck, the proper coolant mixture ratio should be tested for proper freezing points. Most technicians check the coolant concentration using a hand-held antifreeze tester. The protection level should be at least -20°F. The other functions would be performed when servicing the coolant system.

3. Technician A says that power loss in batteries during winter driving is helped by battery heaters. Technician B says that power loss in batteries is helped by slightly overfilling the batteries with electrolyte. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. Maintaining battery temperature of approximately 80°F assures a powerful battery. As a battery becomes colder, it weakens. Overfilling a battery has no effect on the strength of the battery.

4. How often should the air tanks be drained on a high- way-driven truck?


A. at the end of each day


B. at the start of each day


C. at the end of the week


D. at the end of every other day

The correct answer is A. Moisture found in the air will be trapped in the tanks every day. In order to keep the tanks and the system in proper running order and trouble free, drain the tanks at the end of each day. Obviously, C and D would allow too much water contamination in the system. B is incorrect because the time would not be sufficient to allow water to build up.

5. What damage is caused by over-greasing?


A. scoring


B. channeling


C. accumulation of grit around greasing points


D. blowing out a bearing seal

The correct answer is C. Accumulation of grit around the greasing points may allow dirt to be fed into the seal, thus causing premature failure. Scoring would be caused by the lack of grease. A blown bearing seal or channeling would not be caused by over-greasing.

6. Technician A says a dead-lined vehicle can be taken out on local trips only. Technician B says a dead-lined vehicle can be used as a back-up vehicle. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is D, neither technician is right. Without regular preventive maintenance, a truck can develop defects that could force it be taken out of service during a roadside inspection. A dead-lined vehicle is one that has been taken off the road due to a severe safety infraction. A dead-lined vehicle may never be taken out on the road for any reason.

7. The fuel/water separator should be drained;


A. daily


B. weekly


C. monthly


D. annually

The correct answer is A. Once water has entered the fuel system, it can cause severe damage to the injection system. To maintain a properly oper-


ating injection system, all water must be removed. Water should be drained at the end of each day. Water enters the fuel system through moisture found in the tank. The quality of the fuel used may also affect the moisture content.

8. The level of fluid in the battery should be:


A. below the plates


B. even with the plates


C. 1/2 inch above the plates


D. completely full

The correct answer is C. The plates found inside the battery must always be submerged. Electrolyte below or even with the plates would allow the plates to be exposed at times, and a com- pletely full battery will leak and possibly explode when the battery heats up.

9. Technician A says that a fluorescent dye can be used when checking for hard-to-find oil leaks. Technician B says that oil leaking from the engine can be seen with a strobe light. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. For hard to find oil leaks, a fluorescent dye can be added to the engine oil, making any leaks clearly visible using a black light. Run the engine for a while and, using the light, check for oil leaks in the engine compartment. If there is a leak, you’ll see the dye leaking from the engine.

10. A temperature check at the outlet vent closest to the evaporator indicates that the A/C system is not cooling properly after 10 minutes of operation. What should the technician do next?


A. consult the service manual for proper specifications


B. check the temperature of the compressor


C. replace the evaporator


D. adjust the compressor belt

The correct answer is A. Air conditioner outlet temperature is checked by inserting a thermometer into the vent closest to the evaporator. Always refer to the service manual for proper specifications.

11. When checking the air conditioning sight glass. Technician A says that a constant stream of foam is an indication that the system should be inspected for a problem. Technician B says this indicates there is oil in the system. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. The bubbles observed in the sight glass are vapor bubbles, which indicates a problem. The bubbles can damage the air conditioner compressor and related components. Therefore, if bubbles exist, the A/C should not be operated. This condition is not normal. The A/C compressor must be on in order to see the bubbles.

12. Technician A says automatic slack adjusters improve brake balance and reduce down time and maintenance costs. Technician B says manual slack adjusters never need adjusting. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. Having the slack adjusters automatically adjust alleviates the need for the driver or technician to adjust them. The result is reduced down time and less maintenance. Also, automatic slack adjusters will maintain brake balance, minimize travel and lessen air consumption. Manual slack adjusters must be constantly adjusted for minimal travel and reduced air consumption.

13. Technician A says that clutch pedal free-play should be approximately 11/2-in. Technician B says that when a self-adjusting clutch is replaced, only an initial adjustment is required. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. As a rule of thumb, clutch pedal free travel should be approximately 11/2 inches. This allows proper seating of the clutch disc. With too little clearance, it is probable that the clutch pressure plate will not fully release. With too much free-play, the possibility exists that the clutch disc will not fully disengage with the clutch pedal fully depressed. When a self-adjusting clutch assembly has been installed, an initial adjustment must be made. Afterwards, no further adjustment is required.

14. Technician A says some EVAP system charcoal canisters have replaceable air filters. Technician B says the EVAP system is designed to help in cold engine operation. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. Some EVAP system charcoal canisters have replaceable air filters. This service will be particularly important for trucks driven in very dusty conditions. B is wrong because it is the EFE system that provides a source of heat to the engine intake system during cold operation via the EVE, or heat riser valve. The rapid heating provides more efficient fuel evaporation and distribution, helping cold driveability.

15. As the oil temperature in the transmission increases:


A. It raises the oil level.


B. It lowers the oil level.


C. There is no change in the oil level.


D. none of the above

The correct answer is A. As liquid heats up, it expands. This requires that the proper grade and type of oil be used, the oil changed regularly, and the oil level maintained.

16. When lubricating a U-joint, if fresh lube can be seen at all bearing seals. This means the:


A. Trunnions are worn and should be replaced.


B. Bearings are worn and should be replaced.


C. Seals are worn and should be replaced.


D. U-joint has been properly lubed

The correct answer is D. Seeing fresh lube at the seals is the only way to determine that the bearings are being completely lubed. There is minor clearance between the bearings and trunnions for lubrication.

17. Technician A says the compressor on an idling engine should build up air pressure to 85-100 psi within 45 seconds. Technician B says the compressor on an engine running at full-governed rpm should build up air pressure to 100-120 psi within 25 seconds. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. With the engine running at idle, the air pressure should build from 85-100 psi within 45 seconds. If the engine is running at full-governed rpm, air pressure should build up Within 25 seconds, and the compressor should maintain a constant pressure of 100-120 psi.

18. When inspecting for excessive steering wheel free-play on a 22-in. steering wheel, which statement is correct?


A. Free-play cannot exceed 6 3/4 inches.


B. Free-play cannot exceed 8 5/8 inches.


C. Free-play cannot exceed 8 1/4 inches.


D. Free-play cannot exceed 7 1/4 inches.

The correct answer is B. Free-play is the amount of movement in the steering wheel that can be created with little effort. Free-play must not exceed 8 5/8 inches.

19. Technician A says that a front tire should be replaced when tread depth becomes less than 4/32 of an inch. Technician B says that a rear tire with less than 2/32 of an inch of tread depth should be replaced. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. The Commercial Vehicle Safety Alliance Out of Service Criteria should be adhered to in order to protect the customer or the fleet the technician works for from having the vehicle stopped on the road. Front tires should be replaced when the depth is less than 4/32-in. Rear tires should be replaced when the depth is less than 2/32-in.

20. When inspecting for proper operation of the brake warning device, Technician A says the warning device--either audible or visible--must operate at or below 60 psi. Technician B says that the low-vacuum indicator must activate at 8 inches Hg. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. Safety warnings are used to alert the operator that a problem exists in the system. On air systems, the low pressure warning notifies the operator of system air depletion by sounding a warning buzzer, and in some cases, illuminating a light on the instrument panel, or both. When the system is depleted to approximately 60 psi, make sure that all indicator signals operate. On hydraulic systems, in the case of a loss of vacuum, a low-vacuum indicator activates when depletion reaches 8-in. Hg.

21. When lubricating the fifth wheel, what type of lube would be recommended?


A. water-resistant lithium-based grease


B. chassis grease


C. EP lithium soap-based grease
D. none of the above

The correct answer is A. The fifth wheel is not a sealed component, which means that a water- resistant grease must be used in order to properly lubricate it. If water should mix with the lubricants described in answer B or C, it will break down the grease and cause premature failure.

22. Technician A says that mud flaps must be used only if a vehicle is driven off-road. Technician B says that mud flaps should be used on a tractor if driving without a trailer. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is B. Mud flaps should always be used when any wheel is unprotected by a trailer. Mud flaps are mandatory only on highway-driven vehicles.

23. A driver of a combination vehicle says that when a trailer is connected to the tractor, the trailer turn signals do not work. However, when the trailer is disconnected, the tractor turn signals work OK. Technician A says to check for power at the green and yellow wires of the light cord plug. Technician B says to check the fuse for the tractor turn signals. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. The green and yellow wires in the light cord plug supply current to the trailer turn signals. If the tractor fuse that operates the turn signals was blown, the signals on the tractor would also not work.

24. A truck with air brakes has developed an air leak between the compressor and the primary reservoir. Air has completely leaked out of the system. What component should be checked first.


A. one-way check valve


B. dual inversion valve


C. two-way check valve


D. tractor protection valve

The correct answer is A. Each air reservoir employs a one-way check valve that stops the reverse flow of air from the reservoir. This prevents loss of air if there is an air leak between the compressor and the reservoir. The spring brake inversion valve provides back-up braking in the event of a loss of air pressure to the primary system. If a loss occurs, the valve directs secondary air to the spring brakes to facilitate emergency stopping. Two-way check valves sense primary and secondary supply pressure and allow the dominant pressure to actuate the trailer brakes. The same type valve is also used to allow dominant pressure to activate the stoplight switch, and to release the parking brakes. A tractor protection valve senses pressure in one or both lines that carry air to the trailer.

25. Technician A says a truck with darkened power steering fluid is normal. Technician B says a truck with foamy power steering fluid exhibits signs of overheating. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is D, neither technician is right. If the fluid has been overheated, it will be dark in color. Air in the system will cause the fluid to display a foamy appearance.

26. A truck with antilock brakes needs brake fluid. Of the following classifications of brake fluids, which should NOT be used?


A. DOT 3


B. DOT 4


C. DOT 5


D. all of the above

The correct answer is C. DOT 5 is prone to aeration. This means that when the fluid is agitated, tiny air bubbles like those found in a carbonated drink form in the fluid. For this reason, DOT 5 brake fluid is never to be used in an antilock brake system.

27. What grade percentage should a parking brake hold an air-braked vehicle?


A. 10%


B. 15%


C. 20%


D. 22%

The correct answer is C. Per Federal Motor Vehicle Safety Standards, the parking brakes must be able to hold a truck stationary (loaded to its gross weight rating), on a smooth, dry concrete roadway, facing uphill or downhill on a 20% grade.

28. Technician A says the clearance between the bottom edge of the rear impact guard and the ground should not be more than 30 inches. Technician B says the rearmost surface of the horizontal-member of the guard should not be more than 24 inches from the rear of the vehicle. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C. both technicians

are right. The clearance between the bottom edge of the horizontal member of the guard and the ground shall not exceed 30 inches when the vehicle is empty. The rearmost surface of the horizontal member of the guard must be within 24 inches forward of the rear extremity of the vehicle.

29. A truck with air brakes has scored brake drums. When measuring the depth of the marks, what is the maximum measurement not to be exceeded?


A. 0.110-in.


B. 1.000-in.


C. 0.010-in.


D. 0.015-in.

The correct answer is C. Light scoring and abrasion are OK, as long as marks are no deeper than 0.010-in.

30. Technician A says that some white smoke from the exhaust is considered normal. Technician B says excessive white smoke from the exhaust could be the result of unburned fuel passing through the engine. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. While some white smoke is considered normal on cold start-ups, excessive white smoke can be an indication of unburned fuel passing through the engine.

31. Most manufacturers recommend an initial transmission oil change for highway vehicles after a break-in period of:


A. 1000-1500 miles


B. 2500-3000 miles


C. 3000-4000 miles


D. 3000-5000 miles

The correct answer is D. Most manufacturers recommend an initial oil change after the transmission is placed in service, better known as the ‘break-in period.’ This change is typically performed at 3000-5000 miles for over-the-road vehicles. Once the break-in period service has been completed, follow the recommended oil change interval suggested by the manufacturer or service manager, typically around 50,000 miles for on-highway use depending on the vehicle application.

32. The dual integrated push-pull valve is designed to:


A. control air pressure of tractor parking brakes


B. relieve excessive air pressure in the brake system


C. control tractor parking brakes and trailer air


supply


D. apply parking brakes on a straight truck

The correct answer is C. The dash mounted hand brake (or push-pull) control valve comes in two styles, singular or dual integrated. The dual unit controls the parking brakes on the tractor and air supply on the trailer. On a straight truck, a single unit with a yellow parking brake knob is used to control the application of the parking brakes.

33. Technician A says that the batteries on a tractor should be covered by a fixed part of the vehicle. Technician B says a removable cover must be used. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. According to US. Department of Transportation Federal Highway Administration (FHWA) Motor Carrier Safety Regulations, the battery or batteries, unless located in the engine compartment, must be covered by a fixed part of the vehicle, or a removable cover.

34. Normal governor cut-out pressure is set at what pressure?


A. 100 psi


B. 110 psi


C. 125 psi


D. 150 psi

The correct answer is C. Check the governor with the engine running, allowing air pressure to build up in the system. Observe the pressure reading on the dash gauge at which the pressure stops climbing. This is the point of governor cut-out, which should be at approximately 125 psi.

35. The driver of a diesel-powered truck that is mainly operated in the cold weather is complaining that the engine spins slowly upon starting. Technician A says the battery(s) should be charged before testing. Technician B says the starter should be checked first. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. The battery should be checked and charged as needed before testing. The starter may not Operate if the voltage at the battery is below 9.6 volts. Be sure the battery is rated to meet or exceed the vehicle manufacturer's recommendations.

36. The fuel system has been serviced on a diesel engine. Technician A says after the fuel system has been opened, the system has to be bled. Technician B says in some cases, bleeding is not needed. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. After the fuel system has been serviced, the technician should try to start the engine. If the engine runs smoothly after a few minutes, the fuel system most likely does not have to be bled. However, if the engine either does not start or runs rough, the fuel system must be bled.

37. The percentage of coolant/water in a cooling system should be:


A. 70/30


B. 60/40


C. 50/50


D. 40/60

The correct answer is C. To function properly, the cooling system must be completely filled With a 50/50 mix of coolant and water.

38. The alternator/voltage regulator is designed to keep voltage output on a 12-volt system at:


A. 12.5-13.5 volts


B. 13.0-14.0 volts


C. 13.5-14.5 volts


D. 14.5-15.5 volts

The correct answer is C. The function of the alternator/voltage regulator is to keep the system voltage within a predetermined range, typically 13.5 to 14.5 volts on a 12-volt system.

39. Engine vibrations can be attributed to all of the following EXCEPT:


A. turbocharger imbalance


B. loose power steering pump


C. cracked vibration damper


D. loose U-joint

The correct answer is D. Turbocharger imbalance, a loose power steering pump, and a cracked vibration damper can all contribute to engine vibration. If the vibration is equal to engine rpm, and steadily increases when the engine rpm is raised, look for those components that spin directly with engine rpm such as the crankshaft, flywheel or vibration damper. If the vibration is faster than engine rpm, it usually can be attributed to the camshaft, gears or pulleys. A loose U-joint will cause driveline vibration at certain speeds.

40. Technician A says if an area no larger than 10% of the total brake lining is contaminated with fluid, the spot can be cleaned. Technician B says uneven lining wear can be cleared up by properly adjusting the brakes. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. If the lining is otherwise OK, but an area no larger than 10% of the total lining area is contaminated, the spot can be cleaned with the appropriate solvent (not gasoline or another substitute). However, this isn’t the safest option, as it could lead to brake imbalance if done improperly. Lining wear should be even around the circumference of the brake assembly, and inboard-to-outboard. More wear on the bottom, on top or on one side could very likely indicate that peripheral brake hardware is worn. If that is the case, the brakes cannot be properly adjusted.

41. The brake lining on a tractor is being inspected. A high ridge has been found on the inside edge of the linings. Technician A says the ridge makes drum removal easier. Technician B says the ridge helps to keep water and contaminants out of the brake area. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. A high ridge on the inside edge of the linings prevents a lip being etched into the drum and makes drum removal easier. It also helps to keep water and contaminants out of the brake assembly. Tapered lining wear should not be confused with the ridge on the inside edge of the linings.

42. What type of radiator is designed to accommodate today’s aerodynamic trucks?


A. crossflow


B. fullflow


C. downflow


D. lowflow

The correct answer is A. Crosstlow radiators allow for a lower hood height on today‘s aerodynamic trucks. Coolant enters a tank on one side of the radiator and flows across through the radiator core to the other tank, and out to the engine. However, most heavy-duty trucks still employ the downflow type of radiator, where coolant enters the top tank and flows downward through the bottom tank and out to the engine

43. What is the psi variation when an air governor is adjusted 1/2 turn?


A. 2 psi


B. 4 psi


C. 6 psi


D. 8 psi

The correct answer is D. Each 1/4 turn of the governor adjustment screw can raise or lower the pressure settings approximately 4 psi. Therefore, when the screw is adjusted 1/2 turn, the pressure will be raised or lowered approximately 8 psi. To raise the pressure setting, turn the adjustment screw counter-clockwise. To lower the setting, turn the screw clock-wise

44. What does the acronym SCA stand for?


A. suppressed camshaft angle


B. supplemental coolant additive


C. sensor cam adjustment


D. selective crankshaft application

The correct answer is B. Supplemental coolant additives (SCAs) are used in coolant to provide additional protection against corrosion, and to extend the life of antifreeze. These SCAs contain polymers and detergents, and are designed to replenish important coolant chemical concentrations that normally dissipate during normal engine operation. SCAs are an important additive for some engines to help prevent cylinder liner pitting. It is crucial to fol- low SCA guidelines very carefully.

45. Excessive exhaust smoke can be caused by any of the following EXCEPT:


A. insufficient air for good combustion


B. defective or clogged aftercooler


C. oil leakage into combustion chambers


D. external head gasket leak

The correct answer is D. While an external head gasket leak may cause smoke from the engine compartment, it will not contribute to excessive exhaust smoke. Insufficient combustion air, a defective aftercooler and oil leakage into the combustion chamber will directly contribute to excessive exhaust smoke.

46. A truck has lost air pressure to the primary system. Technician A says the spring brake inversion valve will direct secondary air to the brakes. Technician B says the two-way check valve will block secondary air to the brakes. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. Most trucks are equipped with a spring brake inversion valve to provide back-up braking in the event of a loss of air pressure to the primary system. If a loss occurs, the valve directs secondary air to the spring brakes to facilitate emergency stopping.

47. Technician A says a turbocharger wastegate actuator stuck in the open position could cause lack of power and turbocharger boost. Technician B says an inoperative turbocharger will produce white smoke from the exhaust. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. A turbocharger wastegate actuator that is stuck in the open position can be the cause of too little boost and low power. An inoperative turbocharger will contribute to incomplete combustion, causing black smoke. Unburned liquid fuel, coolant leaking into the cylinders, faulty glow plugs or engine components causing low compression will produce white smoke.

48. What is an often overlooked procedure when a technician is checking for engine oil leaks.


A. checking the oil viscosity


B. checking crankcase pressure


C. checking the crankshaft seal


D. checking the valve cover gasket

The correct answer is B. Engine oil leaks can also be caused by something technicians often over-look--excessive crankcase pressure--Which can be caused by worn rings or excessive cylinder wall or liner clearances. These problems allow an unusual amount of combustion blowby gases to enter the crankcase, Where the gases can push oil past seals and gaskets that are in good condition.

49. By adjusting a percent-of-charge switch, some high-rate discharge (load) testers will test a battery with a charge as low as:


A. 10%


B. 15%


C. 20%


D. 25%

The correct answer is D. Some high-rate discharge testers will test a battery as low as 25% charged by adjusting a percent-of-charge switch. Since hydrometer readings indicate only the chemical condition, the battery should be subjected to a high-rate discharge (or load) test to determine its ability to deliver current under load.

50. U-bolt clamping force is being checked with a brass hammer, and the sound being made is a dull thud. Technician A says the U-bolt is clamping properly. Technician B says the U-bolts should be retorqued at specific intervals. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is B. Retorquing U-bolts at the required intervals is the only way of ensuring reliable service and optimum component life. The spring stack will often feel solid even if the U-bolt clamping force is too weak to do the job. You can get a fairly good indication of proper clamping force if you rap the U-bolt with a brass hammer. If the sound you get is a dull thud, it isn’t clamping properly, regardless of pull-around torque. If the sound you get is a ringing sound, the bolt is probably clamping fairly effectively.

51. A truck has just been towed in. Just before the breakdown, the driver noticed a severe engine vibration accompanied by a loud knocking noise. When the engine is inspected, the crankshaft is found to be broken. Which of the following could have caused the problem?


A. bent flywheel


B. loose vibration damper


C. broken engine mount


D. bent crankshaft pulley

The correct answer is B. A defective, loose, cracked or incorrect vibration damper can cause severe engine vibration and crankshaft breakage.

52. During a scheduled maintenance visit, a truck’s drive belts were replaced. After about one thousand miles, one of the belts shows accelerated wear and must be replaced again. Technician A says the belt was adjusted too tight. Technician B says the pulleys are misaligned. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is B. If the belt pulleys are misaligned, the belt enters the pulley on an angle, and belt wear is accelerated. A belt that is too tight places too much tension on the pulley drive bearings, and could cause the bearings to fail prematurely.

53. Air bubbles that appear In the radiator coolant are an indication of:


A. coolant leaking into a cylinder


B. intake valve leakage


C. external head gasket leakage


D. none of the above

The correct answer is A. If coolant is leaking into a cylinder, combustion gases will also be able to escape into the cooling system. When this happens, air bubbles will appear in the radiator coolant when the engine is running.

54. A medium-duty truck with a gasoline-powered engine is experiencing an excessive knocking noise during acceleration. Technician A says the valve clearance is excessive and the valves have to be adjusted. Technician B says a higher quality fuel should be used. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

54. The correct answer is B. Low quality fuel will ignite prematurely in the cylinder and cause knocking on acceleration. If valve clearance was excessive, a ticking noise would be heard coming from the top of the engine at all times, not just during acceleration.

55. There is excessive black smoke coming from the exhaust system of a diesel-powered truck. Of the following, which ls MOST LIKELY the cause?


A. blown head gasket


B. worn rings


C. stuck open thermostat


D. worn valve seals

The correct answer is C. A stuck open thermostat allows coolant to circulate throughout the engine at inappropriate times. This makes the engine run cooler than normal. When this happens, the extreme heat needed for the combustion process is not achieved, causing a richer air/fuel mixture and black smoke from the exhaust.

56. Technician A says approved safety glass must be used on the windshield only. Technician B says the glass must display National Highway Transportation Safety Administration (NHTSA) markings. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is B. Approved safety glass must be used on Windshields and windows, and must display markings in letters and numerals of the size specified, the symbol ‘DOT’ and a manufacturer’s code mark, which is assigned by NHTSA.

57. Technician A says the two types of trouble codes stored in the ECM are called inactive and reactive. Technician B says trouble codes can tell the technician exactly what is wrong with the vehicle. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is D, neither technician is right. Diagnostic systems store active and inactive codes. Active codes describe a failure that is currently affecting the engine. Inactive codes are malfunctions that have been active in the past. Trouble codes do not describe the necessary repair but rather indicate in which circuit the problem is. It is then necessary to perform more precise diagnostic tests to determine the necessary repair.

58. While performing a safety check On a truck, Technician A says the horn must be audible from a minimum of 200 feet. Technician B says wipers must operate at a minimum of 45 cycles per minute. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. The horn(s) must be audible from approximately 200 feet away, and the Wipers should operate at a minimum of 45 cycles per minute.

59.A truck cab equipped with an air suspension exhibits a loss of air pressure on one side only. A technician inspects the system and finds that there are no leaks. What could be the problem?


A. inoperative air brake control valve


B. cab height intake port blockage


C. kinked cab height air hose


D. defective air compressor

The correct answer is C. A kinked cab height air hose will not allow air to the particular cab air suspension component and therefore only that component will not work. An inoperative air brake control valve and defective air compressor would affect the braking system first. A blockage in the intake port of the height valve would cause both sides of the cab suspension to be inoperative.

60. Upon routine inspection of a medium-duty gasoline engine, oil has saturated one of the drive belts. Of the following, which is MOST LIKELY the cause?


A. leaking EGR hose


B. leaking rear main oil seal


C. leaking A/C compressor seal


D. leaking PCV hose

The correct answer is C. Since the A/C compressor has the closest proximity to the belts, a leaky compressor Seal will most likely saturate the belts. A slightly leaking valve cover gasket will allow oil to leak down the sides of the engine. A leaky rear main oil seal will allow oil to leak through the bell housing, and a faulty EGR hose will cause a vacuum leak, not an oil leak.

61. A truck with an electronically controlled diesel engine is suffering from a lack of power on acceleration. Technician ,A says the throttle cable may be binding. Technician B says the throttle position sensor may be defective and to check for trouble codes. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is B. Since the engine is electronically controlled, there is no throttle cable. The next step would be to check the ECM for trouble codes. Many "electronic test instruments, such as scan tools and computer software, are manufactured for the sole purpose of reading/clearing these codes and obtaining information from the ECM.

62. A growling noise is coming from the alternator when the engine is running. Technician A says the alternator belt may be too tight, causing the alternator bearing to wear. Technician B says the belt is worn and should be replaced. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. A tighter than normal alternator belt will put undue stress on the alternator bearing and cause premature bearing wear. This condition may be indicated by a growling noise coming from the front of the alternator when the engine is running.

63. The function of the voltage regulator is to:


A. increase voltage when demand exceeds 14.5 volts


B. decrease voltage to below 13.5 volts when there is no demand


C. stabilize voltage output between 13.5 and 14.5 volts


D. keep voltage steady at 12 volts

The correct answer is C. The voltage regulator’s function is to stabilize voltage output from the alternator and keep it within a predetermined range. Typically, on a 12-volt system the range is from 13.5 to 14.5 volts.

64. A routine check is being performed on a truck’s lighting system. When the cab door is opened, the dome light is inoperative. What should the technician do next?


A. replace the bulb


B. check the circuit for opens or shorts


C. replace the fuse


D. look for an override switch

The correct answer is D. Some vehicles may have an override switch for this function. Make sure the switch is in the ON position. If the switch is in the ON position, and the dome light does not come on, then the technician should proceed with further diagnosis.

65. The driver of a diesel-powered truck With a vacuum-assisted hydraulic brake system is complaining of an extremely hard pedal when stopping. A technician dis- connects the brake booster check valve hose at the valve and installs a vacuum gauge. The engine is started and no vacuum is found at this point. Of the following, which is MOST LIKELY the problem?


A. clogged intake manifold hose


B. inoperative vacuum pump


C. defective check valve


D. defective brake booster

The correct answer is B. Since diesel engines have no manifold vacuum, they must use an external source to create the power assist needed for stopping. The brakes in this case are vacuum assisted, so no vacuum at the hose connected to the check valve would indicate a problem with the vacuum pump.

66. Technician A says that blue marks on a brake rotor are signs of overheating. Technician B says that light scores in the rotor are acceptable, as long as they are less than 0.020-in. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is A. Blue marks on the rotors do indicate that the rotor at one time was excessively hot due to a malfunction in the brake system. Light scoring is acceptable, but not more than 0.010-in.

67. A truck equipped with an automatic transmission is shifting erratically, making noise, and leaking oil from the dipstick tube. Upon inspection, the transmission fluid is found to be foamy. Technician A says the fluid could be aerated. Technician B says the transmission breather may be clogged. Who is right?


A. Technician A only


B. Technician B only


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. Aerated fluid causes cavitation, noises and irregular shifting due to the lack of consistent fluid coupling inside the converter. Air in the system will also cause the fluid to display a foamy appearance. A clogged breather can force fluid up into and out of the dipstick tube.

68. Upon inspection, the front tires of a truck exhibit a featheredge wear pattern. This wear pattern is a direct result of incorrect:


A. camber


B. air pressure


C. vehicle height


D. toe

The correct answer is D. If a tire has too much toe-in or toe-out, the tire is not traveling straight down the road. Feathering is a common condition where one edge of the tread will wear more than the other edge.

69. Technician A says tires must be checked for proper inflation when cold. Technician B says that if one tire on a dual-tire setup goes flat, the vehicle can still be operated. Who is right?


A. Technician A only


B. Technician 8 only


C. Both A and B


D. Neither A or B

The correct answer is D, neither technician is right. Tires can be checked when cold or hot, as long as the technician understands that when air is heated, it expands and pressures will be different. Running dual wheels with one tire flat causes critical overheating of the tire carrying the entire load.

70. A tractor with a trailer connected to it exhibits a loud clunking noise in the rear of the cab, accompanied by excessive movement at the trailer kingpin. Of the following, what is the MOST LIKELY cause?


A. cracked frame


B. misadjusted locking wedge


C. inadequately lubricated fifth wheel


D. loose fifth wheel stops

The correct answer is B. A misadjusted locking wedge can cause the trailer kingpin to move back-and-forth, which will cause a loud clunking when the vehicle is operated.

71. Gladhands are used to:


A. provide a proper way to get into the tractor


B. provide a means to connect the trailer air brake system


C. connect the trailer to the fifth wheel


D. none of the above

The correct answer is B. Gladhands provide a means to connect to a trailer's air brake system. Usually provided in pairs, one gladhand controls the emergency/parking brake and the other controls the service brakes.

72. What is the purpose of the tractor protection valve?


A. senses air pressure in the tractor


B. helps the trailer maintain air pressure


C. keeps the trailer load balanced


D. senses air pressure to the trailer

The correct answer is D. A tractor protection valve senses pressure in one or both lines that carry air to the trailer. This valve closes in order to keep air pressure in the tractor system in the event of a breakaway or excessive air leak in the trailer air system, allowing for emergency tractor service brake operation.

73. Which of the following is NOT a requirement for rear impact guards?


A. they must display the manufacturer’s name and address


B. they must possess the letters DOT


C. they must be used on all tractors


D. rear impact guards are optional on trailers

The correct answer is D. Rear impact guards are required to be mounted on the back of trailers, semi-trailers and trucks (except tractors and drive-away-towaway trucks) to reduce the number of serious injuries or deaths when small vehicles collide with the rear of the vehicle. The impact guard must meet Federal Motor Vehicle Safety Standards (FMVSS) as to its construction, energy absorption, and labeling. The guard must display its manufacturer’s name and address, the month and year of manufacture, and the letters DOT, constituting that the guard manufacturer conforms to all DOT requirements.

74. Technician A says when oil is being changed on a diesel engine; the engine should be at operating temperature. Technician B says discolored oil is a sign that the engine is operating properly. Who is right?


A. Technician A


B. Technician B


C. Both A and B


D. Neither A or B

The correct answer is A. Warm engine oil flows better than cold oil, and allows for more suspended impurities to be flushed out of the oil pan. Usually, when there’s some kind of discoloration, it can be attributed to coolant or fuel mixed in with the oil. When changing oil during normal intervals, look for any discoloration in the oil that may provide a clue of possible contamination or engine failure.

75. Technician A says that one of the tools used to align tandem rear axle alignment is a straightedge. Technician B says if a tandem rear axle is out of alignment there must be worn components because there is no adjustment. Who is right?


A. Technician A


B. Technician B


C. Both A and B


D. Neither A or B

The correct answer is A. To inspect the rear alignment, clamp a straightedge to the frame just ahead of the forward rear axle and make sure it is at 90 degrees to the frame. In order to adjust and correct these measurements, most vehicles are equipped with an adjustable torque leaf or torque arm.

76. Brake shoes are being inspected on a truck with an air brake system. Some of the lining is exhibiting uneven wear around the circumference of the brake assembly. What should the technician do next?


A. check for heat checks in the drum


B. check for worn brake hardware


C. adjust the brakes


D. uneven wear is normal and is no cause for concern

The correct answer is B. Lining wear should be even around the circumference of the brake assembly, and inboard to outboard. More wear on the bottom, on top, or on one side could very likely indicate that peripheral brake hardware is worn.

77. Which of the following is NOT essential to proper ABS operation?


A. sensor adjustment


B. output voltage


C. tire size


D. steering knuckle size

The correct answer is D. Proper ABS operation depends upon a number of factors, including but not limited to tire size, electronic sensor operation and adjustment, and sensor output voltage. Sensors are located at the knuckle on steering axles and inboard of the rear drum on drive axles. Steering knuckle size or configuration has nothing to do with proper ABS operation.

78. Diesel engine EGR systems are designed to:


A. reduce heavy engine nitrogen levels


B. supply the engine with more nitrogen oxides


C. reduce nitrogen oxide emissions


D. help the engine run leaner

The correct answer is C. EGR reduces emissions of Nitrogen Oxides (NOx) by limiting the amount of oxygen introduced into the cylinder. A portion of the exhaust is re-routed back into the combustion chamber, reducing combustion temperature.

79. Technician A says an engine flush should be per formed after a major cooling system component is replaced or the engine is overhauled. Technician B says that in most cases, used Ethylene Glycol is considered hazardous waste. Who is right?


A. Technician A


B. Technician B


C. Both A and B


D. Neither A or B

The correct answer is C, both technicians are right. Manufacturer’s recommendations will govern flushing intervals. However, it’s a good idea to flush and fill the system after an engine overhaul, if a major cooling system component has been repaired or replaced, or after the antifreeze has been drained. In most cases, used Ethylene Glycol is considered hazardous waste and should be disposed of in accordance with local laws.

80. Which one of the following procedures is used to inspect the steering linkage.


A. pitman check


B. steering force check


C. side-to-side check


D. dry park check

The correct answer is D. The steering linkage can be inspected using a procedure called a ‘dry park check’. With the engine off, have an assistant rotate the steering Wheel back and forth while you inspect the steering linkage joints for looseness. Any side-to-side movement of the steering linkage joints is cause for replacement.