INFO CONCERNING OPERATION OF ELECT. DIGITAL COMPASS

SUBJECT: INFORMATION CONCERNING THE OPERATION OF THE ELECTRONIC DIGITAL COMPASS

VEHICLES AFFECTED: 1991-92 'B' MODELS

There have been some concerns received about the operation of the subject compass mirror. These concerns include start up, calibration, magnetic disturbances and display irregularities. Below are explanations for these concerns.

1. START UP: ------------- The display will normally come up within 60 seconds. If it does not appear within 60 seconds, this may be to where the vehicle is parked and what direction it is facing. If the display does not appear for 60 seconds on a consistent basis, calibrate the unit for both deviation and variation. If the unit continues to take longer than 60 seconds for the display to appear and if directional performance appears to be inaccurate, replace the unit.

2. CALIBRATION: --------------- If the initial calibration does not result in satisfactory operation of the compass, try calibrating the unit in a different location, on a level surface and using two different (180 degrees) opposite directions.

3. MAGNETIC DISTURBANCES: ------------------------- If the compass displays erroneous directions temporarily when operating the vehicle in the vicinity of large metallic structures or electrical/magnetic disturbances (e.g.; bridges, large metallic objects above and below ground, or radio, TV, or microwave towers) this is considered normal. The compass mirror is a magnetic device and is affected by major disturbances to the earth's magnetic field. The compass should return to normal operation once the vehicle is beyond the range of the source of the magnetic disturbance.

4. DTSPLAY IRREGULARITIES: --------------------------- Static electricity can cause temporary abnormalities in the appearance of the compass display area. This condition may result after vigorously rubbing the mirror glass display area in low humidity conditions. A static charge can be induced in the liquid crystal display resulting in partial display characters or segments. This condition will correct itself in about five minutes.

The above information should be reviewed before replacing the unit.

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.