Buick Regal: Automatic Day-Night Mirrors Malfunction
Diagnostic Instructions
- Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
- Review Strategy Based Diagnosis for an overview of the diagnostic
approach
- Diagnostic Procedure Instructions provides an overview of each
diagnostic category
Diagnostic Fault Information
1. Inside and Outside Rearview Mirror Automatic Dimming Malfunction
2. Outside Rearview Mirror Automatic Dimming Malfunction
Circuit/System Description
The inside rearview mirror uses 2 photocell sensors. One sensor is the rear
light sensor, located on the
face side of the mirror, facing the rear of the vehicle. The rear light sensor
is used to determine light
conditions present at the mirror face. The other sensor is the front light
sensor, located on the backside
of the mirror, facing the front of the vehicle. The front light sensor is used
to determine the exterior light
conditions at the front of the vehicle. With a low exterior light condition
detected by the front light
sensor and a high light condition from the rear light sensor, the inside
rearview mirror will automatically
darken the face of the inside rearview mirror and the driver outside rearview
mirror. The inside rearview
mirror provides a signal circuit and a low reference circuit to the driver
mirror face to darken the mirror
when needed.
With the gear selector lever in the REVERSE position and the engine running,
backup lamp control
voltage is supplied as an input to the inside rearview mirror. The mirror
monitors this input to disable the
automatic day-night feature. This allows the driver to see objects in the mirror
clearly when backing up,
regardless of the rear light sensor status.
Reference Information
Schematic Reference
- Inside Rearview Mirror Wiring Schematics
- Outside Rearview Mirror Wiring Schematics
Connector End View Reference
COMPONENT CONNECTOR END VIEWS - INDEX
Description and Operation
Automatic Day-Night Mirror Description and Operation
Electrical Information Reference
- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Verification
1. Ignition ON.
2. Cover the windshield with a blanket or other suitable item.
3. Verify the A10 Inside Rearview Mirror face dims when shining a bright light
into the rear light
sensor
- If the A10 Inside Rearview Mirror does not dim
Refer to Circuit/System Testing - Inside Review Mirror Dimming
Inoperative
- Go to next step: If the A10 Inside Rearview Mirror dims
4. Verify the A10 Inside Rearview Mirror face transitions from dim to bright
while commanding the
Backup Lamps Active and Inactive with a scan tool.
- If the A10 Inside Rearview Mirror does not transition between dim and
bright.
Refer to Circuit/System Testing - Day-Night Disable Malfunction
- Go to next step: If the A10 Inside Rearview Mirror transitions
between bright and dim
states
5. Verify the A9A Outside Rearview Mirror-Driver face dims when shining a
bright light into the
rear light sensor.
- If the A9A Outside Rearview Mirror-Driver does not dim
Refer to Outside Rearview Mirror Dimming Malfunction.
- Go to next step: If the A9A Outside Rearview Mirror-Driver dims
6. Verify the A9A Outside Rearview Mirror-Driver face transitions from dim to
bright while
commanding the Backup Lamps Active and Inactive with a scan tool.
- If the A9A Outside Rearview Mirror-Driver does not transition between
bright and
dim states
Refer to Outside Rearview Mirror Dimming Malfunction.
- Go to next step: If the A9A Outside Rearview Mirror-Driver
transitions between
bright and dim states
7. All OK.
Circuit/System Testing
Inside Review Mirror Dimming Inoperative
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector
at the A10 Inside
Rearview Mirror. It may take up to 2 minutes for all vehicle systems to power
down.
2. Test for less than 10 Ω between the ground circuit terminal 5 and ground.
- Ignition OFF, remove the test lamp.
- Test for less than 2 Ω in the ground circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, repair the open/high resistance in the ground
connection.
- Go to next step: If less than 10 Ω
3. Ignition ON.
4. Verify a test lamp illuminates between the ignition circuit terminal 2 and
ground.
If the test lamp does not illuminate and the circuit fuse is good
- Ignition OFF, remove the test lamp.
- Test for less than 2 Ω in the ignition circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, verify the fuse is not open and there is voltage
at the fuse.
- If the test lamp does not illuminate and the circuit fuse is open
- Ignition OFF, remove the test lamp.
- Test for infinite resistance between the ignition circuit and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for infinite resistance between the signal circuit and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- If infinite resistance, replace the A10 Inside Rearview Mirror
- Go to next step: If the test lamp illuminates
5. Replace the A10 Inside Rearview Mirror.
Day-Night Disable Malfunction
1. Ignition OFF, disconnect the harness connector at the A10 Inside Rearview
Mirror. Ignition ON
2. Connect a test lamp between the control circuit terminal 1 and ground
3. Verify the test lamp turns ON and OFF while commanding the Backup Lamps
Active and Inactive
with a scan tool.
- If the test lamp is always OFF
- Ignition OFF, remove the test lamp, disconnect the harness connector at
the K9 Body
Control Module.
- Test for infinite resistance between the control circuit terminal 1 and
ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, refer to Backup Lamps Malfunction.
- If the test lamp is always ON
- Ignition OFF, remove the test lamp, disconnect the harness connector at
the K9 Body
Control Module, ignition ON.
- Test for less than 1 V between the control circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, refer to Backup Lamps Malfunction
- Go to next step: If the test lamp turns ON and OFF
4. Replace the A10 Inside Rearview Mirror.
Outside Rearview Mirror Dimming Malfunction
1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector
at the A9A Outside
Rearview Mirror-Driver. It may take up to 2 minutes for all vehicle systems to
power down.
2. Test for less than 10 Ω between the low reference circuit terminal 16 and
ground.
- Ignition OFF, disconnect the harness connector at the A10 Inside
Rearview Mirror.
- Test for less than 2 Ω in the low reference circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, replace the A10 Inside Rearview Mirror.
- Go to next step: If less than 10 Ω
3. Ignition ON.
4. Test for less than 1 V between the control circuit terminal 2 and ground.
- Ignition OFF, disconnect the harness connector at the A10 Inside
Rearview Mirror, ignition
ON.
- Test for less than 1 V between the control circuit and ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V replace the A10 Inside Rearview Mirror.
- Go to next step: If less than 1 V
5. Ignition ON, headlamps ON, vehicle in PARK, cover the front light sensor
with a towel or other
suitable item. Shine a flashlight at the rear light sensor.
6. Test for greater than 1 V between the control circuit terminal 2 and ground.
- Ignition OFF, disconnect the harness connector at the A10 Inside
Rearview Mirror, ignition
ON.
- Test for infinite resistance between the control circuit and ground.
- If less than infinite resistance, repair the short to ground on the
circuit.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in the control circuit end to end.
- If 2 Ω or greater, repair the open/high resistance in the circuit.
- If less than 2 Ω, test or replace the A10 Inside Rearview Mirror.
- Go to next step: If greater than 1 V
7. Test or replace A9A Outside Rearview Mirror-Driver.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Inside Rearview Mirror Replacement
- Outside Rearview Mirror Glass Replacement
READ NEXT:
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach
Diagn
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this
diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic
approach.
Diag
SEE MORE:
Removal Procedure
WARNING: Brake Dust Warning
WARNING: Brake Fluid Irritant Warning
1. Raise and support the vehicle.
2. Remove the tire and wheel assembly.
3.
Brake Pipe Fitting(1) - Disconnect.
4. Cap the brake pipe fitting to prevent brake fluid loss and contamination.
5.
Brake Hose Retainer
Diagnostic Instructions
Perform the Diagnostic System Check prior to using this diagnostic
procedure: Diagnostic
System Check - Vehicle
Review the description of Strategy Based Diagnosis: Strategy Based
Diagnosis
An overview of each diagnostic category can be found here: Diagnostic
Proced