Circuit/System Testing

Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the P26 Auxiliary Gauge Module. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 10 Ω between the ground circuit terminal 2 and ground.
- If 10 Ω or greater
1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, repair the open/high resistance in the ground connection.
- If less than 10 Ω
Verify a test lamp illuminates between the B+ circuit terminal 1 and ground.
- If the test lamp does not illuminate and the circuit fuse is OK
1. Test for less than 2 Ω in the B+ circuit end to end.
  - If 2 Ω or greater, repair the open/high resistance in the circuit.
  - If less than 2 Ω, verify the fuse is OK and there is voltage at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
1. Test for infinite resistance between the B+ circuit and ground.
  - If less than infinite resistance, repair the short to ground on the circuit.
  - If infinite resistance, replace the P26 Auxiliary Gauge Module.
- If the test lamp illuminates
Connect the harness connector at the P26 Auxiliary Gauge Module. Ignition ON.
Verify scan tool communicates with the Auxiliary Gauge Module.
- If scan tool does not communicate with the Auxiliary Gauge Module
  Refer to Scan Tool Does Not Communicate with Low Speed GMLAN Device .
- If scan tool communicates with the Auxiliary Gauge Module
Replace the P26 Auxiliary Gauge Module.