Cutlass Supreme FWD V6-189 3.1L (1989)
Engine Control Module: All Technical Service Bulletins
ECM - Revised Memory Updating
SUBJECT:
ECM MEMORY UPDATING (INFORMATION ONLY 1989 CUTLASS CIERA WITH 2.8L ENGINE
MODELS/YEARS: AND 1989 CUTLASS SUPREME WITH 2.8L AND/OR 3.1L V-6 ENGINE
NUMBER:
89-T-16
CORP. REF. NO.: 836540R
DATE:
November 1988
SECTION:
6E
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 stored code 44.
All 60~ 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 build-up, 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 drive wheels. 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.
Repost step no. 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.
