Pinpoint Test A : Four-Wheel Drive (4WD) System Functional Test: Notes
Normal Operation and Fault Conditions
The four wheel drive system functional test will isolate and test each sub-system to determine if the subsystem is functioning properly. If a fault is found, additional testing of the suspect subsystem will be required.
When operating in 2H mode, the transfer case clutch is de-energized and both IWE are unlocked. The TCCM may engage the IWE in 2H mode to speed warm up of the front axle fluid. The transfer case has certain amount of clutch drag which can cause the front driveshaft to spin in 2H mode.
When operating in 4WD modes both IWE are locked. In 4A, the TCCM will apply the clutch when needed to control wheel slip.
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Condition |
|---|---|---|
| TCCM C1979:00 | IWE Solenoid Circuit Failure: No Sub Type Information | This DTC sets when the TCCM detects there is a possible mechanical fault present with the IWE system based on wheel speed message data. When the DTC is present IWE solenoid output shall continue to operate normally. |
Possible Sources
- ATCM
- Front Axle
- Transfer case torque on demand clutch