WINDOW DEFOG./WIPER SWITCH HOT (INSTALL NEW SWITCH)

Subject: REAR WINDOW DEFOGGER AND/OR WIPER SWITCHES BECOME HOT TO TOUCH (INSTALL NEW SWITCH)

Model and Year: 1991 S/T TRUCKS

Some owners of 1991 S/T utility models may comment on a condition where the rear window defogger switch and/or the rear window wiper switch is hot to the touch after the dash lights have been on for a period of time. This condition was corrected in production through the introduction of new switch assemblies which have bulbs that operate at lower temperatures. Vehicles built after the VIN breakpoints listed below have been built with the latest design switches.

Plant GMC CHEVROLET OLDSMOBILE -------------- ------------- ------------ ------------- Pontiac West MO529589 M0198875 ------ Moraine M2548564 M2272059 M2704676 Shreveport M8540761 M8257710 ------

If this condition occurs, a new rear window defogger switch and/or rear window wiper switch should be installed to replace the affected part.

SERVICE PROCEDURE:

1. Disconnect negative battery cable. 2. Remove trim plate retaining screw. 3. Remove trim plate. 4. Disconnect wiper/defogger switch connector(s). 5. Remove switch(s) from trim plate. 6. Install new switch(s). 7. Reconnect wiring connector(s). 8. Reinstall trim plate in dash. 9. Reinstall retaining screw. 10. Reconnect negative battery cable.

SERVICE PARTS INFORMATION

Part Number Description Quantity ----------- --------------------- -------- 15679578 Rear window defogger switch 1 15679579 Rear window wiper switch 1

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.