K 3500 Truck 4WD V8-379 6.2L DSL (1985)
Neutral Safety Switch: All Technical Service Bulletins
Backup Lamps/Tailgate Window Release - Inoperative
8A Cab Electrical
SUBJECT: BACKUP LAMPS OR TAILGATE WINDOW RELEASE INOPERATIVE (INSTALL REVISED SWITCH)
MODELS: 1980 - 1991 LIGHT DUTY TRUCKS WITH AUTOMATIC TRANSMISSIONS
Owners of some 1980-1991 C/K, 1982-1991 G, 1985-1991 M/L, 1984-1991 P2 and P3, 1987-1991 R/V, and 1983-1991 S/T (including LLV) with
automatic transmissions may comment on a condition of inoperative back-up lamps or inoperative tailgate window release. This condition occurs when
the vehicle's gear shift lever is placed in the "reverse" position but the back-up lamps do not illuminate. In addition, on the S/T utility vehicles, the
electric tailgate window release does not release when the transmission gear shift lever is placed in the "park" or "neutral" position and the endgate
window release button is depressed. The park/neutral and back-up lamp switch comes out of adjustment, which does not allow for the contact points to
To correct these conditions, the contact carrier on the park/neutral and back-up lamp switch has been modified to increase switch carrier travel.
1. Disconnect the negative battery cable from the battery.
2. Disconnect the switch assembly harness.
3. Place the gear selector in neutral.
4. Squeeze the tangs on the switch together and remove the switch assembly.
5. Install the new switch assembly (P/N 15679680) by:
aligning the actuator with the cutout in the
steering column jacket.
inserting the tangs into the rectangular
holes and pushing down on the switch
6. Adjust the switch by moving the gear selector to park.
7. Connect the switch assembly harness.
8. Connect the negative battery cable.
9. Check for proper switch operation. Readjust the switch as necessary.
SERVICE PARTS INFORMATION:
Park/Neutral and Back-up Lamp Switch
Parts are currently available from GMSPO.
For vehicles repaired under warranty use: