GM Service Manual Online
For 1990-2009 cars only

Outside Mirror System Components

The power outside mirror system consists of the following components:

    • Driver door switch assembly (DDSA)
    • Driver door module (DDM)
    • Passenger door module (PDM)
    • Driver outside mirror
    • Passenger outside mirror
    • Class 2 serial data circuit
    • Power door serial data circuit
    • DRV MDL 10A fuse, DDSA and DDM logic, DDM internal driver operation
    • PASS MDL 10A fuse, PDM logic and internal driver operation

Driver and Passenger Outside Mirror Operation

In order to control outside rear view mirror adjustments, two switches are contained within the driver door switch assembly (DDSA). These are the mirror select switch and the mirror position switch. The DDSA reports the actvity of these switches to the driver door module (DDM) via the power door serial data circuit.The mirror switches are not serviced separately from the DDSA.

The mirror select switch is used to select which mirror, left or right, is to be moved.

The mirror position switch is used to move the mirror that has been selected to the desired position. When the mirror position switch is activated in a Up, Down, Left, or Right direction, the DDSA recognizes the input and sends this data on to the DDM. Depending on which mirror has been selected for adjustment, the DDM either moves the driver door mirror to the requested position, or sends a power door serial data message to the front passenger door module (PDM) indicating that the passenger door mirror needs to be moved. The PDM then moves the passenger door mirror to the requested position.

Each mirror has two reversible motors for position adjustment. The door modules control the reversible motors by applying battery voltage and ground to these motors.

Door Modules Power and Ground

In order to control outside rearview mirror operations, as well as other door functions, the front door modules must be powered up. For this purpose, battery voltage is supplied from the rear fuse block, through separate circuits, to each front door module. Each front door module is separately grounded through a ground stake. The front door modules also use these power and ground supplies to drive the mirror motors, and to provide power and ground to window and lock switches and door lock actuators. In addition, the driver door module (DDM) uses these power and ground supplies to power the driver door switch assembly (DDSA) and integral mirror control switches.

The DDSA battery voltage circuit is fed, through the DDM, by the DRVMDL 10 amp fuse located in the Rear Fuse Block.

The DDM battery voltage circuit is fed by the DRVMDL 10 amp fuse located in the Rear Fuse Block.

The PDM battery voltage circuit is fed by the PASS MDL 10 amp fuse located in the Rear Fuse Block.

These circuits are in the C1 harness connector of each front door module and must not be confused with the door modules voltage and ground circuits that are used exclusively to drive the power window motors.

LH Mirror Motors

The direction in which the LH mirror moves depends on which mirror motor control circuit the voltage is applied to, and which mirror motor control circuit the ground is applied to. For a LH mirror left movement, the driver door module (DDM) applies battery voltage via the left mirror motor left circuit, and ground via the left mirror motor right circuit to the LH mirror horizontal motor. For a LH mirror right movement, the DDM reverses the polarity and applies battery voltage via the left mirror motor right circuit, and ground via the left mirror motor left circuit to the LH mirror horizontal motor. For a LH mirror up movement, the DDM applies battery voltage via the left mirror motor up circuit, and ground via the left mirror motor down circuit to the LH mirror vertical motor. For a LH mirror down movement, the DDM reverses the polarity and applies battery voltage via the left mirror motor down circuit, and ground via the left mirror motor up circuit to the LH mirror vertical motor.

RH Mirror Motors

The RH mirror operates the same as the LH mirror. For a RH mirror left movement, the front passenger door module (PDM) applies battery voltage via the right mirror motor left circuit, and ground via the right mirror motor right circuit to the RH mirror horizontal motor. For a RH mirror right movement, the PDM reverses the polarity and applies battery voltage via the right mirror motor right circuit, and ground via the right mirror motor left circuit. For a RH mirror up movement, the PDM applies battery voltage via the right mirror motor up circuit, and ground via the right mirror motor down circuit to the RH mirror vertical motor. For a RH mirror down movement, the PDM reverses the polarity and applies battery voltage via the right mirror motor down circuit and ground via the right mirror motor up circuit.

Personalization Option and Memory Mirrors

The vehicle may be equipped with the "personalization package" containing memory seats and memory mirrors. However, the front door modules cannot perform memory mirror functions unless the Personalization Option is activated. The dash integration module (DIM) stores the vehicles Personalization Option setting provided at the assembly plant. The DIM reports this Personalization Option setting to both front door modules, as well as other receiving modules, each time the ignition switch is cycled to RUN. The front door modules then store the Personalization Option setting and examine it before making a memory mirrors adjustment.

The Personalization Option setting stored within the front door modules will not change until the Personalization Option setting within the DIM is changed and the ignition switch then cycled to RUN.

If the Personalization Option is activated on a vehicle that is not equipped with memory, the door modules will erroneously set DTCs B1583, B1593, B1613, and B1623.

Memory Mirrors Operation

The memory mirrors are controlled by the mirror position sensors, the driver door switch assembly (DDSA), and the front door modules. The DDSA decodes memory switch activations while the mirror position sensors provide mirror position information to the front door modules. The front door modules supply voltage and ground to the mirror position sensors, store mirror position information, and apply voltage and ground to run the mirror motors.

For memory operations, each outside rearview mirror has four additional circuits and contains a vertical position sensor and a horizontal position sensor. The position sensors, which are potentiometer type sensors, are attached to the corresponding position motor of each mirror and provide constant information, in the form of feedback voltage to the associated door module, to indicate the vertical and horizontal position of the mirror. Each position sensor of each mirror is wired to the corresponding front door module through four circuits to provide mirror location information in the following manner: Each front door module supplies 5 volts reference voltage through a 5 volt reference circuit, and ground through a mirror sensor low reference circuit, to the position sensors. Each front door module also supplies 5 volts through the vertical position sensor signal circuit, and, 5 volts through the horizontal position sensor signal circuit, to the corresponding position sensor. When the mirror motors run, the resistance of the attached sensors vary, which in turn, varies the feedback voltage to the door module. Feedback voltage for each sensor varies between 0.25 volts and 4.75 volts.

When mirror positions are programmed into the personalization package, the front door modules store the positions indicated by the feedback voltages of the position sensors. When a memory recall is requested, the door modules compare the feedback voltages indicated by the current mirror positions to the stored feedback voltages. The door modules then move the mirrors until the current feedback voltages match the stored feedback voltage levels.

Memory Mirrors -- Parallel Parking Mode

If the vehicle is equipped with memory mirrors, it is equipped with the parallel parking mode feature. For this feature, the driver door module (DDM) communicates with the powertrain control module (PCM) over the class 2 serial data circuit. When the gear selector is shifted to reverse, the PCM transmits this status via a class 2 message to the DDM. The DDM sends this message on to the front passenger door module (PDM) over the power door serial data circuit. The PDM then applies battery voltage and ground to the vertical motor of the RH outside rear view mirror to tilt the mirror down 7 degrees. This allows the driver to see the curb while parallel parking. When the gear selector is shifted out of reverse, the PDM powers the verticla motor of the RH outside rearview mirror to return to the previous position.

Heated Mirrors

The mirrors heat during the defrost/defog cycles for the rear window. The heated mirrors are connected to the driver door module (DDM) and the front passenger door module (PDM). The DDM receives a class 2 message from the instrument panel cluster (IPC) via the rear integration module (RIM) commanding the heated mirrors ON. The DDM also examines information from the dash integration module (DIM) to determine if vehicle conditions are correct for the heated mirrors function to occur. If conditions are correct, the DDM then applies voltage and ground to the driver side mirror heater element, and sends a power door serial data message to the PDM to apply voltage and ground to the passenger side mirror heater element.

The DDM supplies battery voltage to the LH outside rearview mirror heating element via the feed circuit, and ground via the return circuit.

The PDM supplies battery voltage to the RH outside rearview mirror heating element via the feed circuit, and ground via the return circuit.

Automatic Day/Night Feature Operation

The automatic day/night feature of the driver outside rearview mirror is controlled by the inside rearview mirror. The inside rearview mirror supplies a signal and a low reference to the driver outside rearview mirror. The voltage on the signal circuit of the driver outside rearview mirror varies between 0.5-1.5 volts depending on light conditions present at the inside rearview mirror. At night, with the automatic day-night feature enabled, the driver outside rearview mirror will automatically darken with the inside rearview mirror to reduce the glare from the headlamps from behind. The voltage on the signal circuit of the driver outside rearview mirror will be near 1.5 volts. In the daytime, the mirrors are in a normal state. The voltage on the signal circuit of the driver outside rearview mirror may be less than or near 0.5 volts. Refer to Automatic Day-Night Mirror Description and Operation in Stationary Windows for further description and operation of the inside rearview mirror.

Turn Signals Indicator Feature

The driver door switch and passenger door switch receive voltage from the BCM turn signal supply voltage circuits for the mirror turn signals. The door switches have no function or control of the mirror turn signals other than a pass through connection for the circuits.