ECM - Memory Updating

88buick15

Bulletin: 89-6E-2

Date: Nov '88

Ref. No.: 89-028-6E

Corp. Ref. No.: 836540
SUBJECT: ECM MEMORY UPDATING

MODELS AFFECTED: 1989 REGALS

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. Start the engine, and shift the transaxle to "drive".
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.