Exam 44: Four- and All- Wheel Drive

How can manual locking hubs be tested?

Identify the gear selector positions available in a conventional 4WD transfer case.

A typical four-wheel drive truck is equipped with a longitudinally based engine, a manual or automatic transmission, and a transfer case.

Technician A says AWD systems are based on FWD systems that use a viscous clutch, center differential, or transfer clutch to transfer power from the transaxle to a rear driveline. Technician B says an AWD system is based on RWD systems that use a transfer case, front drive shafts, and front axle assemblies to drive the front wheels. Who is correct?

Technician A says a vacuum motor engages some 4WD front axles. Technician B says an electrical motor engages some 4WD front axles. Who is correct?

Usually the drive chain is replaced if the transfer case is being serviced.

Identify the main internal components in a conventional transfer case.

Front axle disconnect systems are being discussed. Technician A says the systems use a vacuum motor to disengage and engage the right side axle shaft from the differential. Technician A says an electric motor is used to engage and disengage the axle. Who is correct?

Two technicians are discussing the difference between 4WD and AWD. Technician A says AWD does not have an interaxle differential lockout. Technician B says AWD does not have a low range. Who is correct?

Four-wheel drive operation modes are being discussed. Technician A says 4-low, as compared to 4-high, increases wheel torque. Technician B says 2-low is available on most 4WD vehicles. Who is correct?

Most all-wheel drive vehicles are based on an RWD platform.

Full-time 4WD vehicles require locking hubs at the front wheels.

In a viscous clutch, when the silicone fluid is heated, it ______.

Technician A says mismatched tire sizes can cause transfer case noise. Technician B says incorrect tire inflation pressure can cause transfer case noise. Who is correct?

A four-wheel drive vehicle requires four drive shafts.

The speed sensors used in a 4WD or AWD system are best checked with a ____________________.

Technician A says the transfer case uses a chain to transfer torque from the transmission to the front driveshaft. Technician B says the transfer case uses spur or helical cut gearsets to transfer torque to the front driveshaft. Who is correct?

____________________ are checked by grasping each front tire at the front and rear and pushing the wheel inward and outward. Then grasping the tire at the top and bottom and pushing the wheel inward and outward.

Technician A says the transfer case splits torque from the transmission to the front and rear axles. Technician B says viscous clutch units can be overhauled. Who is correct?

A ratcheting sound from an automatic locking hub may be caused by ______.