Circuit/System Testing
- Verify that the TCCM fuse, fuse 12, underhood fuse block, is NOT open.
- If fuse 12 is OPEN, test the battery positive voltage for a short to ground, TCCM Harness X3 pin B.
- Ignition ON. Engine OFF
- Disconnect the X1 harness connector at the transfer case encoder motor (TCEM).IMPORTANT: When test probing harness terminals, it is imperative to use the proper test probe from the most current version of the J 35616 GM terminal test kit. Use of an improper test probe may deform the terminal, resulting in intermittent open conditions.
- Using the purple probe J 35616-4A, test for a 3-4 V diagnostic voltage between the Motor B circuit, TCEM X1 Pin D, and a good ground.
- If the voltage is greater than the specified range, test the Motor B circuit for a short to voltage. If all circuits and connections test normal, replace the TCCM.
- If the voltage is less than the specified range, test the Motor B circuit for an open/high resistance or short to ground. If all circuits and connections test normal, replace the TCCM.
- Using the purple probes J 35616-4A, test for 3-4 V between the Motor B circuit, TCEM harness X1 pin D, and the TCEM Motor A circuit, TCEM harness X1 pin E.
- If the voltage is greater than the specified range, test the Motor A circuit for a short to voltage. If all circuits and connections test normal, replace the TCCM.
- If the voltage is less than the specified range, test the Motor A circuit for an open/high resistance or short to ground. If all circuits and connections test normal, replace the TCCM.
- If all circuits and connections test normal, replace the TCEM.