Diagnosing the 1984 & 1985 Automatic Day/Night Mirror is very simple and straight forward when following tne Electrical Trouble-shooting manual. However, it should be pointed out that the ambient (daylight) sensor is on the windshield side of the mirror near the Distance Dial, and the headlight sensor is below the mirror near the Off/Auto switch. When checking the mirror operation, it will be necessary to cover the ambient sensor with a dark cloth and be sure enough light is striking the headlight sensor so the mirror will respond automatically. This will cause the mirror to go to the night position as if another car were following behind. Remove the cloth, and with adequate light available at the ambient sensor, the mirror should go to the day posi- tion. There will be some delay between changes to prevent unnecessary switching of the mirror when passing under street lights, etc.
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.