GM Service Manual Online
For 1990-2009 cars only

Outside Mirrors Circuit Description With Memory

Memory Mirrors

Each outside power mirror contains two motors. One motor moves the mirror up and down. The other motor moves the mirror left and right. The direction the motors turn depends on the supply voltage polarity sent to the motors. Mirror selection (left or right) and movement (up/down or left/right) is controlled by operating the power mirror switch. When the power mirror switch is operated, battery voltage is applied to the module select/position inputs. This causes the module to output voltage to the mirror motors, moving the mirror to the commanded position.

The mirror motor position sensors are used in order to remember the mirror positions. These sensors are potentiometers contained in the power mirror drive unit. As the mirror motors turn, the potentiometer resistance is varied. The mirror position is determined by the voltage level sent to the memory seat/mirror module. The voltage level is stored in order to remember the mirror positions under the following conditions:

    • The set memory button is pushed.
    • Either memory select button (1 or 2) is pressed.

Memory Seat/Mirror Module Diagnostic Modes

In order to enter the manual diagnostic modes of the memory seat/mirror module, turn the ignition switch to the OFF position. If the ignition is set to RUN or START while the module is in a diagnostic mode, the module exits the diagnostics and sounds 3 beeps.

The mode 1 diagnostics of the memory seat/mirror module is used in order to test the following inputs:

    • Memory
    • Seat
    • Mirror switch

In order to enter mode 1 of the manual diagnostics, ensure that the memory seat diagnostic connector is grounded. You may tape the diagnostic connector into the harness. When the connector is grounded, the module beeps once in order to acknowledge entrance into the mode 1 diagnostics. Ensure that the connector remains grounded throughout the mode 1 diagnostics. If ground at the connector is lost for more than 5 seconds, the module exits the diagnostics and sounds 3 beeps. The following functions are disabled during mode 1:

    • Memory
    • Seat
    • Mirror

In order to test the inputs, the memory, seat, or mirror switch is operated as if performing that function. Each time the memory seat/mirror module sees an input from a switch, the module beeps once. If a switch is operated and the module does not beep, the module did not receive the input. There may be a problem with the switch or wiring from the switch to the module.

The mode 2 diagnostics is used in order to test the seat and mirror position sensor inputs. In order to enter mode 2 of the manual diagnostics while in the mode 1 diagnostics, the ground is removed from the memory seat diagnostic connector. Then, ground is reapplied within 5 seconds. The module beeps twice in order to acknowledge that the module has entered the mode 2 diagnostics. If ground at the connector is lost for more than 5 seconds, the module exits the diagnostics and sounds 3 beeps. The seats and mirrors move during the mode 2 diagnostics. In order to test the inputs, one of the following components is operated to command the seat or mirror to move:

    • Manual seat
    • Power mirror switch

The position sensor input for that direction is tested. For example, if the seat is commanded to move forward, the module tests the forward/back position sensor. If the module sounds a beep when a switch is being operated, the module senses a discontinuity in that direction's position sensor. This means that there may be a problem with the position sensor or the wiring from the switch to the position sensor.

In order to exit the diagnostic mode, perform one of the following actions:

    • Remove ground from the memory seat diagnostic connector for more than 5 seconds.
    • Put the ignition in RUN or START.

When the module exits the diagnostic mode, the module sounds 3 beeps in order to acknowledge that the module is no longer in the diagnostic mode.

Outside Mirrors Circuit Description Without Memory

Move the outside power mirror switch in the desired direction in order to adjust the power mirrors from the interior of the vehicle.

Each outside power mirror has two reversible motors. One motor adjusts the mirror view up and down. The other motor adjusts the mirror view right and left. The driver operates the power mirror switch in the following directions in order to control the polarity of the voltage motors:

    • UP-DOWN
    • LEFT-RIGHT

The mirror select switch directs these control voltages to one of the following components:

    • RH outside power mirror
    • LH outside power mirror

Battery voltage is applied through the up contacts of the power mirror switch to the up-down motor in the left outside power mirror under the following conditions:

    • The mirror select switch in the LEFT position.
    • The power mirror switch held in the UP position.

The left outside power mirror up-down motor has a path to ground through the following components:

    • The mirror select switch
    • The up contact of the mirror control switch

The LH outside power mirror up-down motor runs and turns the mirror up.

When the power mirror switch is pushed to the DOWN position, the LH outside power mirror up-down motor receives voltage. However, the voltage polarity is reversed. The motor runs in the opposite direction.

The LH outside power mirror left-right motor operates similarly. When the power mirror switch is moved to the LEFT position, battery voltage is applied through the following components to the left-right motor in the left outside power mirror:

    • The left contacts of the mirror select switch.
    • The left contacts of the power mirror switch to the battery.

The LH outside power mirror left-right motor is grounded through the left-right contact of the power mirror switch. The LH outside power mirror left-right motor runs. This turns the mirror to the left.

If the power mirror switch is pushed to the RIGHT position, the same motor receives voltage. However, the voltage polarity is reversed. The motor runs in the opposite direction.

The right outside power mirror works the same way as the left outside power mirror under the following conditions:

    • The mirror select switch is moved to the right position.
    • The power mirror switch is operated.