Pinpoint Tests AO: The Compass Is Inaccurate

Instrumentation, Message Center and Warning Chimes

Pinpoint Tests

Pinpoint Test AO: The Compass Is Inaccurate

Normal Operation

The auto-dimming interior mirror communicates the vehicle direction to the Instrument Cluster (IC) through the compass communication data plus circuit VMC31 (GY/BU) and communication data minus circuit VMC30 (BU/GY). The magnetic fields generated by the earths north and south poles are divided into zones that differ from each other with respect to how the magnetic fields appear. The magnetic north can change by up to 4 degrees between zones and become noticeable across multiple zones. The compass zone must be set to the correct zone for the compass to read accurately. Factors within the vehicle may affect the ability of the auto-dimming interior mirror to accurately read the magnetic north. Calibrating the compass allows the auto-dimming interior mirror to compensate for vehicle factors that influence the accuracy of the compass.

NOTE: Outside factors such as bridges, steel structures, tall buildings and power lines also affect compass accuracy.

This pinpoint test is intended to diagnose the following:

- Zone setting
- Calibration
- Auto-dimming interior mirror



PINPOINT TEST AO: THE COMPASS IS INACCURATE

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AO1 CHECK THE COMPASS ACCURACY


- Position the vehicle and observe the compass display as follows:





- Does the compass display as indicated?

Yes
The compass is OK.

No
GO to AO2.

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AO2 CHECK THE COMPASS ZONE SETTING AND CALIBRATION


- Set the zone. REFER to Compass Zone Adjustment Compass Zone Adjustment.
- Calibrate the compass. REFER to Compass Zone Adjustment Compass Zone Adjustment.
- Does the compass calibrate correctly?

Yes
The compass is OK. The concern may have been caused by an incorrect zone setting or the compass was out of calibration.

No
INSTALL a new auto-dimming interior mirror. SET the zone. REFER to Compass Zone Adjustment Compass Zone Adjustment. CALIBRATE the compass. REFER to Compass Calibration Compass Calibration. TEST the system for normal operation.

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