GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1999 🢒 Astro - 2WD 🢒 Body and Accessories 🢒 Interior Trim 🢒 Electronic Compass Calibration

The electronic compass is capable of distinguishing 8 primary directions:

    • North
    • Northeast
    • East
    • East-southeast
    • South
    • South-southwest
    • West
    • West-northwest

The compass calibration procedures establish a base direction from which the compass can work. Once the compass has been properly calibrated, the digital display indicates the direction of vehicle travel.

Under normal circumstances, compass calibration is only necessary about every 2 years. However, recalibration may be necessary if any of the following events occur:

    • The vehicle is involved in a collision, or subjected to any other jarring force sufficient to disturb the inherent vehicle magnetic field.
    • The vehicle is operated a sufficient distance away from the point of initial calibration, in another part of the country, for example.

Calibration

The compass is self-calibrating, eliminating the need to manually set the compass. Occasionally, the compass on a new vehicle may appear to operate erratically, causing the CAL symbol to illuminate. In order to correct this problem, drive the vehicle through 3 complete 360 degree turns. The CAL symbol will then turn OFF and the compass will function normally. If you install a new compass, a similar calibration procedure is used. Calibrate a new compass as follows:


    Object Number: 9020 Size: SH
  1. Turn ON the ignition.
  2. Simultaneously depress and hold both the ON/OFF button (3) and the U.S./METRIC button (4) on the overhead console for approximately 10 seconds, or until the display reads CAL.
  3. Drive the vehicle through 3 complete 360 degree turns. The CAL symbol will turn off when the compass is calibrated, and the compass will function normally.

Variance

Electronic Compass Operation Variance is defined as the angular difference between magnetic north and geographic north. In some areas of the country, this difference is great enough to cause false compass readings. Set the variance for a particular location as follows:

  1. Determine the vehicle's location on the zone map.

    2. Note the zone number.

  2. Simultaneously depress and hold both the ON/OFF button and the U.S./METRIC button. The display will turn OFF.
  3. After 5 seconds, VAR will appear on the display. Release both buttons.

    4. Object Number: 300847 Size: SH
  4. Press the U.S./METRIC button (4) until the correct zone number appears on the display.
  5. Press the ON/OFF button in order to enter the geographical zone number.

    6. The compass is now adjusted for variance.