ECM MEMORY UPDATING REPAIR PROCEDURE REVISION

VEHICLES AFFECTED: ALL 1989 A/J/L/W WITH 2.8L - 1988 1/2 AND 1989 STE ALL WHEEL DRIVE MODELS WITH 3.1L V-6

The following service information revises the recommended service procedure to update the Electronic Control Module (ECM) "keep alive" memory on the subject models in order to assure proper engine operation. Failure to follow this procedure may result in a temporary lean engine operation, engine will not continue to run, rough idle, or a check engine light with a stored Code 44.

All 60 degree v-6 engine calibrations for 1989 production and service include a feature which stores in ECM memory the Idle Air Control Valve (IACV) position at which the engine idles. Each vehicle will have a unique value, depending on the throttle body base air rate setting, deposit buildup, etc. The IACV position information is continuously updated, during vehicle operation, and is stored in the ECM "keep alive" memory when the engine is turned off.

NOTICE: IF THE ECM IS WITHOUT BATTERY POWER FOR ANY REASON, THEN THE IACV POSITION INFORMATION FOR A STABLE SATISFACTORY ENGINE IDLE IS "LOST" AND IS REPLACED WITH A "DEFAULT" VALUE.

To correct the IACV position information due to an absence of battery power and improve the engine idle, perform the following procedure:

1. Restore the battery power and place air conditioning controls (if equipped) in the "off" position.

2. Firmly apply the parking brake and block the drivewheels. Start the * engine, and shift the transaxle to "drive" for automatics or "neutral" for manuals.

3. Allow the engine to run until the engine cooling fan has cycled once, or a maximum of 10 minutes.

4. Turn the ignition key to the "off" position for at least 5 seconds.

5. Repeat Step #2.

6. Allow engine to run for at least 5 minutes.

This procedure will allow the ECM memory to be updated with the "correct" IACV position, for the vehicle, and provide 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.