Circuit/System Testing
- Verify that no DTC within the range of U1001-U1254 exists as current or history in any module.
- Ignition OFF, disconnect the harness connector of 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, replace the faulty 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, replace the faulty module.
- Test for less than 1 ohm 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 in the class 2 serial data circuit(s) between the non-communicating module and the module that displays the DTC.
- If greater than the specified range, test the serial data circuit(s) for open/high resistance.
- If all circuits test normal, replace the module that is not communicating.