GM Service Manual Online
For 1990-2009 cars only
  1. If there is a strong magnetic field in the area near the mirror, the compass circuit cannot compensate for the magnetic field.
  2. Inspect for the following possible magnetic fields:
  3. 2.1. Magnetic antenna mount
    2.2. Magnetic notepad holder
    2.3. Any similar magnetized items in the area of the mirror.
  4. In order to fix a problem with a strong magnetic field, perform the following steps:
  5. 3.1. Remove the magnetic item.
    3.2. Turn the mirror OFF for 30 seconds.
    3.3. Turn the mirror back ON.
    3.4. If the mirror comes back on displaying direction or a C, inform vehicle owner of offending magnetic part. Refer to Compass Calibration Description .
    3.5. If the mirror still displays all segments, replace the mirror assembly.