Pinpoint Test A : AWD (All-Wheel Drive) System Functional Test
- Normal Operation and Fault Conditions
The AWD system is an active system, which means it not only responds to wheel slip between the front and rear axles but also has the ability to anticipate wheel slip and transfer torque to the rear wheels before the slip occurs. The AWD system is active all the time and requires no input from the operator. The AWD system continuously monitors vehicle conditions and automatically adjusts the torque distribution between the front and rear wheels. During normal operation, most of the torque is delivered to the front wheels. If wheel slip between the front and rear wheels is detected, if the vehicle is under acceleration or if the vehicle is in a handling event, the AWD system increases and distributes torque to the rear wheels as needed. When the AWD system is functioning properly, there should be no perceived speed difference between the front and rear axles when launching or driving the vehicle on any uniform surface. Traction should be similar to a part time 4WD system in 4H (4X4 HIGH), but have no binding in turns .
Possible Sources
- Wiring, terminals or connectors
- Wheels/tires
Visual Inspection and Pre-checks
- ABS sensor wiring
- Constant velocity joints
- Driveshaft
- Halfshafts
- Tire size
- Tire wear
- U-joints
- WARNING: WARNING: When directed to drive the vehicle as part of this test, drive the vehicle on a hard surface in an area without traffic to prevent a crash. Failure to follow these instructions may result in personal injury.
- NOTE: Check related modules for Diagnostic Trouble Codes (DTCs). If Diagnostic Trouble Codes (DTCs) are set in other modules, diagnose those Diagnostic Trouble Codes (DTCs) first before continuing.
- A1 CHECK FOR ACTIVE TORQUE COUPLING SOLENOID LOCK
- Drive the vehicle on a dry, hard surface in turns while applying the accelerator pedal.
Is driveline wind-up present in turns?
Yes GO to Pinpoint Test E No GO to A2 - A2 CHECK ABS WHEEL SPEEDS
- Using a scan tool, drive the vehicle at 30 mph (48 km/h) and monitor the following wheel speed sensor PIDs:
- Left Front Wheel Speed Sensor (LF_WSPD)
- Left Rear Wheel Speed Sensor (LR_WSPD)
- Right Front Wheel Speed Sensor (RF_WSPD)
- Right Rear Wheel Speed Sensor (RR_WSPD)
Are all 4 wheel speeds within 1.2 mph (2 km/h) of each other?
Yes GO to A3 No Refer to: Anti-Lock Brake System (ABS) and Stability Control . - Using a scan tool, drive the vehicle at 30 mph (48 km/h) and monitor the following wheel speed sensor PIDs:
- A3 CHECK VEHICLE ACCELERATION IN A STRAIGHT LINE
- Perform 3 accelerations from mph (km/h) to 30 mph (48 km/h) in a straight line (1 each with low, medium and full accelerator pedal application).
Does the vehicle pulsate or shudder while accelerating?
Yes GO to Pinpoint Test E No GO to A4 - A4 CHECK VEHICLE TURNING ABILITY
- Drive the vehicle in a fully locked turn, on dry pavement, at 5 mph (8 km/h).
Does the vehicle bind in the turn or resist turning?
Yes GO to Pinpoint Test E No GO to A5 - A5 CHECK TORQUE AT THE REAR WHEELS
- Using the diagnostic scan tool, energize the Active Torque Coupling (ATC) solenoid to a constant 90% applied.
- On dry pavement, drive the vehicle in a fully locked turn at 5 mph (8 km/h).
Does the vehicle bind in the turn or resist turning?
Yes END the active command. CLEAR all DTCs if set. End of System Functional Test. The system is operating correctly at this time. No CHECK the Power transfer unit (PTU). Refer to: Transfer Case .