Automatic Dimming Inside Mirror Test/Replacement

Automatic Dimming Inside Mirror

Test/Replacement

'03 model With Navigation:

NOTE: Before testing, check the No. 9 (7.5 A) fuse in the driver's under-dash fuse/relay box. No. 7, 10, 11, 13, 14 and 15 terminals are On Star switches microphone power, ground and signal line.




1. Disconnect the 3P connector (A) from the OnStar switches and microphone/automatic dimming inside mirror (B).
2. Check for continuity between No. 3 terminal and body ground.

- If there is continuity, go to step 3.
- If there is no continuity, check for:
- an open in the wire.
- poor ground (G 581).

3. Check for voltage between No.12 terminal and body ground with the ignition switch ON (II).

- If there is battery voltage, go to step 4.
- If there is no voltage, check for:
- blown No. 9 (7.5 A) fuse in the driver's under-dash fuse/relay box.
- an open in the wire.

4. Check for voltage between No. 16 terminal and body ground with the ignition switch ON (II) and gear position switch in [R] or shift lever position in "R".

- If there is battery voltage, replace the mirror assembly.
- If there in no voltage, check for:
- an open in the wire.
- faulty reverse relay.
- faulty A/T gear position switch (A/T).
- faulty back-up light switch (M/T).

'01-02 models, '03 model Without Navigation:

1. Remove the spotlight.




2. Disconnect the 3P connector (A) from the automatic dimming inside mirror (B).
3. Check for continuity between No. 3 terminal and body ground.

- If there is continuity, go to step 4.
- If there is no continuity, check for:
- an open in the wire.
- poor ground (G 581).

4. Check for voltage between No.1 terminal and body ground with the ignition switch ON (II).

- If there is battery voltage, go to step 5.
- If there is no voltage, check for:
- blown No. 9 (7.5 A) fuse in the driver's under-dash fuse/relay box.
- an open in the wire.

5. Check for voltage between No. 2 terminal and body ground with the ignition switch ON (II) and gear position switch in [R] or shift lever position in "R".

- If there is battery voltage, replace the mirror assembly.
- If there in no voltage, check for:
- an open in the wire.
- faulty reverse relay.
- faulty A/T gear position switch (A/T).
- faulty back-up light switch (M/T).