BASE IDLE ADJUSTMENT REVISED DIAGNOSTICS. Cadillac Cimarron 1988

MODELS AFFECTED: 1988 CIMARRONS

The following service information revises the recommended diagnostic procedure referenced on page 6E3-B-7 of the 1988 Service Information Manual.

Some 1988 Cimarrons may experience a condition of rough, unstable or incorrect idle speed, and/or stalling at idle.

This condition may be caused by a loss of idle air control valve (IACV) position at which the engine idles. During normal vehicle operation the ECM learns the correct position for the IACV to maintain proper engine idle speed. Each vehicle will have a unique value, depending on the throttle body base air rate setting, deposit buildup, etc. This information is retained in the ECM's "keep alive" memory. If the ECM is without battery power for any reason, then the IACV position information for stable engine idle is "lost" and replaced with a default value.

To repair this condition, perform the following procedure:

1. Restore the battery power and place air conditioning controls in the off position.

2. Start the engine and shift the transmission to "drive" for automatics or "neutral" for manuals.

3. Allow the engine to run approximately five minutes until the normal operating temperature is attained.

4. After attaining operating temperature, allow the engine to idle for an additional two minutes.

This procedure will allow the ECM memory to be updated with the correct IACV position for the vehicle providing a stable idle rpm.

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.