PCM-BCM - Communication Interruption W/Scan Tool Use

9218oldsmobile06

NUMBER: 91-T-156

CORP.REF.NO: 106502

DATE: June 1991

SECTION: 6E3


SUBJECT:
INTERRUPTION OF PCM-BCM COMMUNICATION WHEN A DIAGNOSTIC TOOL IS CONNECTED TO THE ALDL - INSTALL A REVISED MEMCAL

MODELS/YEARS:
1991 TORONADO, TROFEO


Some 1991 Toronado and Trofeo models equipped with 3800 T.P.I. (VIN L) engine, built prior to vehicle number MU306201, (Federal calibration) or MU306180, (California calibration) may have a condition that prevents the PCM from communicating with the BCM when a diagnostic tool is connected to the vehicle's serial data (ALDL) connector. This condition only occurs when a diagnostic tool is connected to the vehicle's ALDL connector.

Should this condition exist on a vehicle, technicians may observe specific functions that are affected.
^ A/C clutch remains on or off.
^ BCM Code 334 (BCM-PCM communication error) is stored.
^ Coolant temperature gauge and tachometer are not displayed.

This condition may lead to improper diagnosis and unnecessary repairs. It is recommended that a new revised calibration mem-cal be installed.

The mem-cals are currently available through GMSPO under the following part numbers.

Axle Scanner Broadcast Service
Ratio I.D. Code Part #

3.06 Fed. 1464 AXMU 16162582

3.06 Calif. 1474 AXMW 16162586