Circuit/System Testing

WARNING: This page is about a different car, the 2009 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

Using the DTC Descriptor and Diagnostic Aids above, determine the module that is not communicating that should be tested.
Ignition OFF, disconnect the harness connector at the module that is not communicating.
Ignition ON, verify that a test lamp illuminates between all battery positive voltage circuits and ground.
- If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, test or replace the module.
Verify that a test lamp illuminates between all ignition voltage circuits and ground.
- If the test lamp does not illuminate, test the circuit for a short to ground or an open/high resistance. If the circuit fuse is open, also test the positive voltage outputs of the module for a short to ground. If the circuits test normal, test or replace the module.
Test for less than 10 ohms between the module ground circuits and ground.
- If greater than the specified range, test the ground circuit for open/high resistance.
Test for less than 1 ohm on the high speed GMLAN serial data circuits between the non-communicating module and the module that displays the DTC.
- If greater than the specified range, test the serial data circuits for open/high resistance.
If all circuits test normal, test or replace the module that is not communicating.