GM Service Manual Online
For 1990-2009 cars only

Outside Mirror Description and Operation Heated Mirrors

Heated OSRV Mirror

On vehicles equipped with heated outside rearview mirrors (OSRV), the driver door module (DDM) and passenger door module (PDM) controls the activation of the mirror heaters. Upon receiving a Class 2 message indicating a request for heated mirrors, the DDM (and PDM for the passenger side) will activate the mirror heater output. The mirror heaters will remain active until a new message is received indicating rear defogger is to be deactivated (either by driver input or by expiration of a calibrated timer).

Outside Mirror Description and Operation Power Mirrors

Power Mirror System

Power Mirror System Components

The power mirror system consists of the following components:

    • Driver door module (DDM)--Class 2 module with integrated switches and requires programming when replaced
    • Passenger door module (PDM)--Class 2 module with integrated switches and requires programming when replaced
    • Power mirror direction switch--Supplied power by the DDM and is a 4-position momentary switch that provides a voltage signal input to the DDM for up, down, left/extend, and right/retract with a mirror switch activation
    • Mirror select switch--Supplied power by the DDM and is a 3-position switch that allows the operator to select the left or right mirror and also a neutral/fold position
    • Left outside power mirror--Contains both the vertical and horizontal mirror motors and is serviced as a complete mirror assembly
    • Right outside power mirror--Contains both the vertical and horizontal mirror motors and is serviced as a complete mirror assembly
    • Body control module--Class 2 module that requires programming when replaced, serves as the power mode master and is the main message handler
    • DDM 10A fuse--Located in the rear fuse block and is hot at all times
    • PDM 10A fuse--Located in the rear fuse block and is hot at all times
    • Memory switch, if equipped with memory mirrors--Supplied power by the DDM and provides a voltage signal to the DDM upon a switch activation
    • Horizontal and vertical position sensors, if equipped with memory mirrors--Supplied a 5-volt and low reference by the DDM/PDM and provides a variable voltage signal to the DDM/PDM that is proportional to mirror position
    • Park/neutral position (PNP) switch, if equipped with memory mirrors--Provides transmission gear selection information to the powertrain control module (PCM) and is used for memory recall and mirror tilt in reverse functions
    • Powertrain control module, if equipped with memory mirrors--Class 2 module that requires programming when replaced and provides class 2 message indicating transmission gear selection
    • Liftgate module, if equipped with memory mirrors--Class 2 module that requires programming when replaced, is the keyless entry receiver and provides a class 2 message on a keyless unlock transmission that is used for memory recall functions
    • Driver information center (DIC), if equipped with memory mirrors--Part of the instrument cluster which is a class 2 module that requires programming when replaced and is used to personalize the memory recall and mirror tilt in reverse functions
    • Fold motor in each of the outside mirrors, if equipped with power fold mirrors--Provides extend and retract movements of the mirror and is serviced as a complete mirror assembly

Each of the outside power mirrors contains 2 reversible motors to provide horizontal and vertical movement of the mirror glass. The vertical motor operates the up and down directions and the horizontal motor operates the left and right directions. If equipped with power folding mirrors, each outside power mirror will contain a reversible fold motor to operate the extend and retract functions. Each of the mirror motors are circuit breaker protected.

Power Mirror System Controls

The power mirror switch incorporates a 3-position mirror select switch and a 4-position mirror direction switch. The mirror select switch allows the operator to select the mirror to be moved by rotating counterclockwise to the L position for the left power mirror, rotating clockwise to the R position for the right power mirror, or the center which is the neutral/fold position. The mirror direction switch is a 4-position switch that allows the operator to move the selected mirror up, down, left, or right. The mirror direction switch also functions as the folding mirror switch. When the selector switch is in the neutral/fold position, activate the mirror direction switch to the left to extend the mirrors and right to retract the mirrors.

Power Mirror System Operation

The power mirror switch receives power from the DDM through the battery supply voltage circuit and the DDM fuse. The left and right mirror positions of the select switch and 4 positions of the direction switch, when active, will provide a battery voltage signal to the DDM through their respective signal circuits. If the selector switch is placed in the L position and the up switch is depressed, a battery voltage signal will be supplied to the DDM through the driver mirror select switch signal and the mirror motor up switch signal circuits. The DDM upon receipt of these signals will provide battery voltage to the mirror motor left/up control circuit and ground to the mirror motor down control circuit and the mirror will move up. The remainder of the driver mirror functions operate in the same manner as described above except the DDM will supply battery voltage and ground to the appropriate control circuits for the direction selected. If the passenger mirror is selected and a direction switch is activated, the DDM sends a class 2 message to the PDM indicating that the passenger mirror was selected and the direction to be commanded. The PDM will then supply battery voltage and ground to the appropriate control circuits for the direction selected.

Memory Mirror System

Memory Mirror System Controls

The driver door module (DDM) and the passenger door module (PDM) are capable of storing mirror positions and controlling the mirrors to these positions to the preferred settings of 2 different drivers. Each driver will be able to personalize the memory system by positioning the mirrors and seats to their preferred settings. Then press and hold the memory 1 or memory 2 button until an audible chime is heard and the current mirror positions will be stored into memory of the DDM and PDM. Seat position will be stored in the memory seat module (MSM). Once the mirror and seat positions have been stored into memory, a momentary memory 1 or memory 2 switch activation will supply the DDM a battery voltage signal. The DDM, upon receipt of the memory switch signal, with the transmission in park or neutral, will then drive the driver mirror to the corresponding stored memory position. The DDM will also send a class 2 message to the PDM and MSM indicating that a memory switch activation occurred. The PDM will then drive the passenger mirror and the MSM will drive the driver seat to the corresponding stored memory position. The memory system can also be controlled by any of the following, if programmed, using the driver information center (DIC) to enable/disable the features:

    • Auto exit/entry seat positioning
    • Mirror and seat position recall on a keyless entry unlock activation
    • Mirror and seat position recall on ignition key insertion
    • Mirror tilt in reverse

For further information on programming and configuration, refer to Driver Personalization in Personalization.

Memory Mirror System Operation

Mirror position is determined by both horizontal and vertical position sensors in each of the power mirrors. The DDM and PDM supplies a reference voltage and a low reference to these sensors and determines mirror position through the horizontal and vertical position signal circuits.

The memory switch receives power from the DDM through the battery supply voltage circuit and the DDM fuse. The DDM upon receipt of a memory switch signal input or an appropriate class 2 message from the body control module (BCM), the DDM, and the PDM will then supply battery voltage and ground to the appropriate power mirror motors through the mirror motor control circuits to move the mirrors to the predetermined positions.

Mirror Tilt in Reverse Controls

This feature is capable of tilting the passenger side power mirror when the transmission is placed in reverse to provide enhanced visibility during parking or backing maneuvers. This feature is turned OFF or ON through the DIC. The passenger mirror on domestic vehicles can not be changed from the factory setting, but on export vehicles, the passenger mirror position may by changed using the same procedure as the driver mirror. For further information, refer to Driver Personalization in Personalization.

Folding Mirror System

Folding Mirror System Controls

When the mirror select switch is in the neutral/fold position, it allows the operator to retract or extend the outside rearview mirrors from a single switch. The mirror fold switch incorporates solid state circuitry to allow this single switch input to alternately perform both extend and retract functions.

Folding Mirror System Operation

The mirror fold switch receives power through the battery supply voltage circuit and the EXT LPS fuse and a constant ground. The mirror extend and retract control circuits are connected to ground through the normally closed contacts of the mirror fold switch. When the mirror fold switch is activated, the solid state circuitry will energize either the extend or retract relay, depending on the last function, which supplies battery voltage to the fold motor through one of the control circuits. The other control circuit is connected to ground through the normally closed contacts in the mirror fold switch and the mirror extends or retracts.