Drive Axle (Front) - Will Not Disengage

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GMC NUMBER: 91-7D-175

GROUP: 7D Transfer Case

DATE: January 1992

CORPORATE
NUMBER: 167402


SUBJECT: FRONT AXLE WILL NOT DISENGAGE (INSTALL REVISED VACUUM ACTUATOR SWITCH)

MODELS: 1983 - 1991 T-TRUCKS (4WD JIMMY/SONOMA)


Owners of some 1983-1991 T-trucks may comment about inappropriate front axle disengagement. This condition may be due to a corroded transfer case vacuum actuator switch. To correct this condition a revised switch (P/N 15664811), constructed of noncorrosive stainless steel, should be installed.

SERVICE PROCEDURE:





The vacuum switch is located on the left upper side of the transfer case (Figure 1).

1. Raise the vehicle and support with suitable safety stands.

2. Remove the vacuum lines from the switch.

3. Remove the corroded switch from the transfer case.

4. Install a revised switch (P/N 15664811). Coat the threads with thread sealant.

5. Connect the vacuum lines.

6. Lower the vehicle.

7. Check for oil leaks at the threads and vacuum leaks around the vacuum lines.


SERVICE PARTS INFORMATION:

Part Number Description
15664811 Vacuum Actuator Switch

Parts are expected to be available on 1/27/92. In case of limited inventory, parts will be placed on 400 control to waive VIP surcharges. Only verifiable emergency orders will be accepted. SPO will make every effort to obtain parts. However, the part will be shipped premium transportation at the dealer's expense and all other order types will be placed on backorder until the 400 control is removed.

WARRANTY INFORMATION:
For vehicles repaired under warranty use:

Labor Operation: K4120

Labor Time: 0.4 hr.