Circuit/System Testing
WARNING: This page is about a different car, the 2008 GMC Yukon XL, 2008 GMC Yukon, 2008 Chevrolet Tahoe, 2008 Chevrolet Suburban, and 2008 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
The incremental sensor impulse signal circuit, incremental direction signal circuit, incremental sensor low reference circuit, and the 8-volt reference circuit will need to be check for a short to ground, open, high resistance, and a short to voltage using the following steps.
- Disconnect the connector at the transfer case actuator and check the 8-volt reference signal on pin G at the transfer case actuator with a DMM, ignition on, the voltage should read 7.8-8.2 volts.
- If the voltage does not read within the specifications then check the 8-volt reference circuit for a short to voltage, open, high resistance, or short to ground. If the circuit checks good and the voltage is out of range replace the transfer case control module, program, and perform the motor learn procedure. If the circuit checks good continue to next step.
- At the transfer case actuator, with a jumper harness short the 8-volt reference circuit pin G to the incremental impulse signal pin E and note the voltage on the scan tool data display.
- If the voltage does not read 7.8-8.2 volts check the incremental impulse signal circuit for and open, high resistance, short to ground, or short to voltage. If the circuit checks good then go to the next step.
- Check the incremental direction circuit for an open, short to ground, high resistance, or a short to voltage by probing pin F at the transfer case actuator and pin 14 and transfer case control module connector X2.
- If all circuit test good replace the transfer case actuator and perform the motor learn procedure.