Front Axle Will Not Engage
Front Axle Will Not EngageTest 1-6:
Test 7-17:
Circuit Description
The front axle control circuit consists of a front drive axle clutch solenoid, which is electronically controlled by the transfer case shift control module. The front drive axle clutch solenoid opens and closes a vacuum control valve, allowing vacuum to apply and release a clutch pack inside the front axle housing. The transfer case shift control module determines whether or not the clutch pack has been applied or released, based on a signal from the front axle switch mounted on the front axle housing assembly. The front axle is normally locked, or engaged, during AUTO 4WD, 4WD Hi, and 4WD LO modes. The front axle is unlocked, or disengaged, only during 2HI or NEUTRAL modes.
Test Description
The numbers refer to the step numbers on the diagnostic table.
2. This step helps determine whether the transfer case shift control module has electronic control of the front axle actuator.
3. This step tests the operation of the front axle switch by determining whether the state of the front axle switch is correct.
4. This step determines whether correct vacuum is supplied to the front axle actuator.
5. This step tests for proper voltage supplied to the front axle solenoid.
6. This step helps determine continuity through the front axle control circuit, testing the wiring and module driver.
7. This step tests the front axle circuit for an open.
8. This step tests the front axle switch for an internal open.
9. This step tests the front axle switch feed circuit for proper voltage.
10. This step tests the front axle switch circuit for an open.