PINPOINT TEST G : The Auto-Dimming Mirror Does Not Operate Correctly
- G1 CHECK THE OPERATION OF THE REVERSING LAMPS
- Ignition ON.
- Move the selector lever through the entire range.
Do the reversing lamps illuminate only in REVERSE?
Yes GO to G2. No REFER to Exterior Lighting , Symptom Chart: Reversing Lamps. - G2 VERIFY THE FORWARD AND REARWARD FACING SENSORS ARE NOT BLOCKED
- Verify the forward and rearward facing sensors are not blocked. Sources of blockage can include:
- stickers, window decals or tags.
- fold-down screens for TVs or DVD players.
- non-Original Equipment Manufacturer (OEM) window tinting.
Were either of the sensors blocked?
Yes If possible, REMOVE the blockage. If the blockage cannot be removed, ADVISE the customer that the blockage will effect the correct operation of the interior auto-dimming mirror. No GO to G3. - Verify the forward and rearward facing sensors are not blocked. Sources of blockage can include:
- G3 CHECK OPERATION OF THE INTERIOR AUTO-DIMMING MIRROR - DAYLIGHT CONDITIONS
- Ignition ON.
- Use a bright lamp to illuminate the forward facing sensor. The mirror should adjust to a high reflectance mode (mirror will be clear).
Does the mirror adjust to the high reflectance (clear) mode?
Yes GO to G4. No INSTALL a new interior auto-dimming mirror. Refer to Interior Rear View Mirror . - G4 CHECK OPERATION OF THE INTERIOR AUTO-DIMMING MIRROR - NIGHTTIME CONDITIONS WITH GLARE
- Ignition ON.
- Select PARK.
- Simulate nighttime conditions with glare:
- Cover the forward sensor with black electrical tape or other dark material.
- Illuminate the rearward facing sensor. The mirror should darken to a lower reflectance mode.
Did the mirror darken to a lower reflectance (darker) mode?
Yes GO to G5. No GO to G7. - G5 CHECK OPERATION OF THE INTERIOR AUTO-DIMMING MIRROR - NIGHTTIME CONDITIONS WITHOUT GLARE
- Ignition ON.
- Select PARK.
- Simulate nighttime conditions without glare by covering the rearward facing sensor. The mirror should adjust to the high reflectance mode.
Did the mirror adjust to the high reflectance (clear) mode?
Yes GO to G6. No GO to G7. - G6 CHECK OPERATION OF THE INTERIOR AUTO-DIMMING MIRROR - NIGHTTIME CONDITIONS WITH THE VEHICLE IN REVERSE
- Ignition ON.
- Simulate nighttime conditions with glare:
- Cover the forward sensor with black electrical tape or other dark material.
- Illuminate the rearward facing sensor (mirror should darken at this time).
- Select REVERSE.
Did the mirror adjust to a high reflectance (clear) mode?
Yes The system is operating normally at this time. ADVISE the customer of the correct operation of the interior auto-dimming mirror. No GO to G7. - G7 CHECK FOR VOLTAGE TO THE INTERIOR AUTO-DIMMING MIRROR
- Ignition OFF.
- Disconnect: Interior Auto-Dimming Mirror.
- Ignition ON.
- Measure:
Without Automatic High Beams
Positive Lead Measurement / Action Negative Lead C9039-1 Ground With Automatic High Beams
Positive Lead Measurement / Action Negative Lead C911-1 Ground
Is the voltage greater than 11 volts?
Yes GO to G8. No VERIFY that BCM fuse 38 (10A) (without automatic high beams) or fuse 34 (10A) (with automatic high beams) is OK. If OK, REPAIR the circuit for an open. If not OK, REFER to the OEM ELECTRICAL WIRING DIAGRAM INTRODUCTION to identify the possible causes of the circuit short. - G8 CHECK FOR GROUND TO THE INTERIOR AUTO-DIMMING MIRROR
- Ignition OFF.
- Measure:
Without Automatic High Beams
Positive Lead Measurement / Action Negative Lead C9039-4 Ground Automatic High Beams
Positive Lead Measurement / Action Negative Lead C911-8 Ground
Is the resistance less than 3 ohms?
Yes Automatic high beams, GO to G10. Rear view camera video display in the mirror, GO to G11. Electrochromatic mirror only , GO to G9 . No REPAIR the circuit. - G9 CHECK FOR VOLTAGE TO THE INTERIOR AUTO-DIMMING MIRROR REVERSE CIRCUIT
- Ignition ON.
- Select REVERSE.
- Measure:
Positive Lead Measurement / Action Negative Lead C9039-9 Ground
Is the voltage greater than 11 volts?
Yes INSTALL a new interior auto-dimming mirror. Refer to Interior Rear View Mirror . No REPAIR the circuit. - G10 CHECK THE Image Processing Module - A (IPM-A) HS-CAN COMMUNICATION
- Ignition ON.
- Using a scan tool, perform the network test.
Did the Image Processing Module - A (IPM-A) pass the network test?
Yes INSTALL a new interior auto-dimming mirror. Refer to Interior Rear View Mirror . No Refer to article 'Module Communications Network', Go to Pinpoint Test AM . - G11 CHECK THE COMMUNICATION CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: BCM C2280B.
- Ignition ON.
- Measure:
Positive Lead Measurement / Action Negative Lead C9039-2 Ground
Is any voltage present?
Yes REPAIR the circuit. No GO to G12. - G12 CHECK THE COMMUNICATION CIRCUIT FOR AN OPEN
- Ignition OFF.
Is the resistance less than 3 ohms?
Yes GO to G13. No REPAIR the circuit. - G13 CHECK THE COMMUNICATION CIRCUIT FOR A SHORT TO GROUND
- Measure:
Positive Lead Measurement / Action Negative Lead C9039-2 Ground
Is the resistance greater than 10, 000 ohms?
Yes INSTALL a new interior rearview mirror. Refer to Interior Rear View Mirror . No REPAIR the circuit. - Measure:

