Circuit/System Testing

Reverse Input Malfunction

1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
2. Ignition ON, park brake applied, vehicle in REVERSE, test for B+ between the supply voltage circuit terminal 9 and ground.
   • If less than the specified value, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, refer to Backup Lamps Malfunction .
3. If all circuits test normal, test or replace the inside rearview mirror.

Outside Rearview Mirror Dimming Malfunction

1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
2. Ignition ON, verify a test lamp does not illuminate between the following circuits and ground:
   • Signal circuit terminal 5
   • Low reference circuit terminal 16
   • If the test lamp illuminates, test the applicable circuit for a short to voltage.
3. Ignition OFF, test for infinite resistance between the following circuits and ground:
   • Signal circuit terminal 5
   • Low reference circuit terminal 16
   • If less than the specified range, test the applicable circuit for a short to ground.
4. Test for less than 100 ohms of resistance between the signal circuit terminal 5 and the low reference circuit terminal 16.
   • If greater than the specified range, test both circuits for an open/high resistance. If the circuit tests normal, test or replace the driver outside rearview mirror face.
5. If all circuits test normal, replace the inside rearview mirror.