Circuit/System Testing

Outside Rearview Mirror Switch Circuit Testing 

1. Ignition OFF, disconnect the harness connector at the outside rearview mirror switch.
2. Test for less than 1 ohm of resistance between the ground circuit and ground.
   • If greater than 1 ohm, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the voltage supply circuit and ground.
   • If the test lamp does not illuminate, repair the voltage supply circuit for a short to ground or an open/high resistance. If the voltage supply circuit fuse is open, also test the signal circuit for a short to ground.
4. If all circuits test normal, test or replace the outside rearview mirror switch.

Outside Rearview Mirror Motor Circuit Testing 

1. Ignition OFF, disconnect the harness connector at the outside rearview mirror motor.
2. Test for infinite resistance between the mirror control circuits and ground.
   • If less than infinite resistance, test the control circuits for a short to ground.
3. Install a test lamp between the control circuit for the particular motor and the common control circuit for the mirror motors. Operate the mirror motor by the mirror switch. The test lamp should illuminate with each command.
   • If the test lamp does not illuminate, test the motor control circuits for an open/high resistance or a short to ground. If the circuits test normal, test or replace the rearview mirror switch.
   • If the test lamp stays ON constantly, test the motor control circuit for a short to voltage. If the circuits test normal, test or replace the rearview mirror switch.
4. If all circuits test normal, test or replace the outside rearview mirror motor.