SER. MANUAL UPDATE SEC.8A I/P ILLUMINATION OPERATION

SUBJECT: MANUAL UPDATE - SECTION 8A INSTRUMENT PANEL ILLUMINATION FEATURE OPERATION

VEHICLES AFFECTED: 1991 CHEVROLET AND BUICK W-CAR

The 1991 Chevrolet Lumina and Buick Regal are equipped with an instrument panel illumination feature which is a function of the light switch. This illumination feature operates as follows:

With any door open or with the light switch in the "DOME" or "INT" position, terminal D of the light switch receives a ground signal from the door jamb switch through the WHT (156) wires (see page 8A-114-1 for Chevrolet and 8A-114-2 for Buick) or internally through the light switch. When the last door is closed and the light switch is not in the "DOME" or "INT" position, or when the light switch is moved from the "DOME" or "INT" position with all doors closed, ground is removed from terminal D of the light switch. The light switch then supplies voltage for about 30 seconds through the GRY (8) wires to illuminate the instrument cluster, radio, heater and A/C control assembly , console PRNDL, ashtray, (steering wheel controls if equipped for Buick) and the front door lock and window switches (see page 8A-117-0 and 8A-117-1 for Chevrolet and page 8A-117-1, 8A-117-2 and 8A-117-4 for Buick).

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.