Drive Axles - Inoperative Differential Locking Switch
89Pontiac23Bulletin Number: 90-7-7
Reference Number: 977144
Publish Date: 10/89
Figure 1 - HYDRA-MATIC 3T40-A All Wheel Drive Transmission:
Subject: INOPERATIVE AND/OR INTERMITTENT CENTER DIFFERENTIAL LOCKING SWITCH (REPLACE SWITCH)
Models
Affected: 1990 PONTIAC 6000 SE 3T40-A/THM A-1
BULLETIN COVERS: Figure 1
An inoperative and/or intermittent Center Differential Locking Switch (43) due to moisture entry during the manufacturing process, which may cause the following concerns:
- AWD LOCK indicator will remain on, but differential will not lock
- ANTILOCK indicator will remain on and ABS operation would be disabled
Vehicles equipped with possible inoperative and/or intermittent differential locking switches were produced between the following VIN breakpoints:
1G2AJ54T6L202602 and 1G2AJ54T6L209333.
SERVICE PROCEDURE:
If an inoperative or intermittent switch is found, replace it with a new one. This procedure can be performed on vehicle.
SERVICE PARTS INFORMATION:
Refer to the following part number whenever replacement of this switch is necessary.
Part Number Description
8665329 Switch, Signal Differential Lock
Parts are currently available from GMSPO.
SERVICE MANUAL REFERENCE:
Whenever on-vehicle service is necessary to any HYDRA-MATIC 3T40-A (THM A-1), refer to Section 7A of your service manual.