Electronic Rear Differential Lock Will Not Disengage
Electronic Rear Differential Lock Will Not Disengage
Circuit Description
The rear differential control circuit consists of an actuator which engages and disengages the rear axle differential lock. The rear differential actuator consists of a coil assembly, and a locking assembly with springs and pins to lock the rear differential, all within the rear differential assembly.
The rear axle differential lock actuator consists of the following circuits:
* The rear differential lock control circuit, which is connected to the transfer case shift control module and supplies battery voltage.
* The rear differential lock return ground circuit, which is also connected to the transfer case shift control module.
Whenever the rear differential lock has been requested the transfer case shift control module provides battery voltage through the rear differential lock control circuit, and provides ground through the rear differential lock return circuit through a current limiting driver.
Whenever a rear differential lock is requested the transfer case must be in 4LO and the vehicle speed must be below 5 km/h (3 mph) for the request to be accepted. The rear differential lock will remain locked up to 32 km/h (20 mph) after which the rear differential lock will disengage.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
2. This step determines if the differential lock is engaged due to an electrical condition or a mechanical condition.
3. This step determines if the differential lock high control circuit is shorted to power and if the differential low reference circuit is shorted to ground.
4. This step indicates the transfer case shift control module needs replaced.
5. This step checks for the possibility of the rear differential mechanically binding causing it to stay on.
