Circuit/System Testing
- With a scan tool, verify DTC U0100-U02FF or DTC U2105-U2199 is not set as current.
- Vehicle OFF, disconnect the applicable control module harness connector.
- Vehicle OFF, test for less than 10 Ω between the applicable control module ground circuit terminal and ground.
- If greater than the specified range, test the ground circuit for an open/high resistance.
- Vehicle in Service Mode, verify a test lamp illuminates between the following circuits of the applicable control module and ground:
- The battery positive voltage input circuits
- The battery positive voltage output circuits
- The ignition voltage input circuits
- The ignition voltage output circuits
- The switched battery positive voltage supply circuits
- If the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuit fuse is open, test the circuit for a short to ground. If the circuit tests normal, replace the applicable control module.
- Vehicle OFF, test for less than 5 Ω between the non-communicating control module GMLAN serial data circuits and the control module reporting DTC U0002.
- If greater than the specified range, test the circuit for an open/high resistance.
- If all circuits test normal, replace the applicable control module.