GM Service Manual Online
For 1990-2009 cars only

Automatic Day-Night Mirror System Components

The automatic day-night mirror system consist of inside rearview mirror.

Automatic Day-Night Mirror System Operation

With the ignition switch in the ON position, ignition 1 voltage is supplied through the CLAMP 15 CRUISE fuse, in the fuse block, to the inside rearview mirror. The inside rearview mirror uses 2 photocell sensors in order to determine light conditions in the front and the back of the vehicle. At night, as the glare of the headlamps from behind increases, the mirror gradually becomes darker in order to absorb the glare. In the daytime, the mirror is in a normal state. With the gear selector lever in the REVERSE position, backup lamp supply voltage is supplied as an input to the inside rearview mirror. The inside rearview mirror will gradually change to a normal state as a result of the backup lamp supply voltage input. Ground for the inside rearview mirror is provided by G103

Inside Rearview Mirror with Memory System Components

The inside rearview mirror with memory system consist of the following components:

    • Inside rearview mirror
    • Memory seat module (MSM)

Inside Rearview Mirror with Memory System Operation

The inside rearview mirror contains two reversible DC motors and two position sensors. One motor adjusts the mirror to the UP/DOWN or vertical position. The other motor adjusts the mirror to LEFT/RIGHT or horizontal position. The MSM controls the mirror direction by changing the polarity of the voltage applied to the motors.

The MSM supplies a 5 volt reference circuit and a low reference circuit to each of the horizontal and vertical position sensors of the inside rearview mirror. The MSM monitors the signal circuits of the position sensors to determine the position of the mirror. When a memory function is requested, the MSM stores the position of the mirror into memory.