SECTION 501-09: Rear View Mirrors
2014 Mustang Workshop Manual
DIAGNOSIS AND TESTING
Procedure revision date: 01/07/2013

Rear View Mirrors — Interior


Special Tool(s)
Fluke 77-IV Digital Multimeter
FLU77-4 or equivalent
Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool
 

Principles of Operation

Interior Auto-Dimming Rear View Mirror

The interior auto-dimming rear view mirror automatically reduces the glare caused by headlamps reflecting in the interior rear view mirror. The auto-dimming feature is disabled when the vehicle is in REVERSE. Power is supplied to the interior auto-dimming mirror when the ignition is in the RUN or ACC position.

The interior auto-dimming rear view mirror has 2 photoelectric sensors that detect forward and rearward light conditions, and based on those inputs, adjusts the reflectance level of the interior rear view mirror to eliminate unwanted glare. The reflectance level of the mirror glass is variable and depends on the amount of rear glare in relation to ambient light conditions in front of the interior mirror.

When the forward sensor detects daytime conditions, the rearward sensor is inactive, and the mirror glass stays in a high reflectance mode. When the forward sensor detects nighttime conditions, the rearward sensor is active and detects glare from the headlights of vehicles approaching from the rear, or other glare producing light sources. To provide increased visibility when backing up, the interior rear view mirror glass will automatically return to a high reflectance mode whenever the selector lever is placed in REVERSE.

If the forward or rearward sensors are blocked, the auto-dimming interior rear view mirror might not work correctly.

Interior Rear View Mirror With Video Display

For vehicles that are equipped with a rear-mounted object detection camera, a video image will be displayed on the LH side of the interior rear view mirror glass when the transmission is in the REVERSE position. For information on the rear-mounted object detection system, refer to Section 413-13 .

 

Inspection and Verification

  1. Verify the customer concern.
  1. Visually inspect for obvious signs of mechanical or electrical damage.

      Visual Inspection Chart

    Mechanical Electrical
    • Interior rear view mirror
    • Smart Junction Box (SJB) fuse 41 (15A)
    • Circuitry
    • LH exterior mirror glass
    • LH exterior mirror
    • Interior auto-dimming rear view mirror
    • Loose or corroded connections
    • Body Control Module B (BCM-B)

  1. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

  1. NOTE: Make sure to use the latest scan tool software release.

    If the cause is not visually evident, connect the scan tool to the Data Link Connector (DLC).

  1. NOTE: The vehicle Vehicle Communication Module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM .

    If the scan tool does not communicate with the VCM :
  1. If the scan tool does not communicate with the vehicle:
  1. Carry out the network test.
  1. Clear the continuous DTCs and carry out the self-test diagnostics for the BCM-B .
  1. If the DTCs retrieved are related to the concern, go to the Body Control Module B (BCM-B) DTC Chart. For all other DTCs, refer to Section 419-10 .
  1. If no DTCs related to the concern are retrieved, GO to Symptom Chart - Interior Mirror or GO to Symptom Chart - NVH .
 

DTC Chart

Diagnostics in this manual assume a certain skill level and knowledge of Ford-specific diagnostic practices. REFER to Diagnostic Methods in Section 100-00 for more information about these practices.



 Body Control Module B (BCM-B) DTC Chart

DTC Description Action to Take
P0801:11 Reverse Inhibit Control Circuit: Circuit Short to Ground GO to Pinpoint Test D .
P0801:12 Reverse Inhibit Control Circuit: Circuit Short to Battery GO to Pinpoint Test D .
P0801:13 Reverse Inhibit Control Circuit: Circuit Open GO to Pinpoint Test D .
All other DTCs — REFER to Section 419-10 .

 

Symptom Chart(s)

Diagnostics in this manual assume a certain skill level and knowledge of Ford-specific diagnostic practices. REFER to Diagnostic Methods in Section 100-00 for more information about these practices.

 
Symptom Chart — Interior Mirror
Condition Possible Sources Action
  • The interior mirror is blemished
  • Interior mirror glass/housing is dirty
  • NOTE: Do not clean the housing or glass of any mirror with harsh abrasives, fuel or other petroleum-based cleaning products.

    • CLEAN the affected interior mirror surface.

    • The interior mirror is damaged
    • The auto-dimming mirror does not operate correctly
    • Obstructed forward or rearward-facing sensor
    • INSPECT for:
      • Stickers, window decals, tags
      • Non-OEM window tinting
    • If possible, REMOVE the obstruction. If the obstruction cannot be removed, GO to Pinpoint Test D to test the interior auto-dimming mirror for correct function.
      • Light source near or inside of vehicle
      • None. Any light source the rearward-facing sensor is exposed to can be considered glare.
        • Vehicle inside garage or tunnel
        • None. Ambient light conditions are similar to nighttime.
          • Fuse
          • Circuitry
          • Interior auto-dimming mirror
          • Body Control Module B (BCM-B)
          • Interior mirror compass concerns
          • —
          • Interior mirror video display concerns
          • —
           
          Symptom Chart — NVH

          NOTE: NVH symptoms should be identified using the diagnostic tools that are available. For a list of these tools, an explanation of their uses and a glossary of common terms, refer to Section 100-04 . Since it is possible any one of multiple systems may be the cause of a symptom, it may be necessary to use a process of elimination type of diagnostic approach to pinpoint the responsible system. If this is not the causal system for the symptom, refer back to Section 100-04 for the next likely system and continue diagnosis.

          Condition Possible Sources Action
          • The interior mirror vibrates/loose
          • Interior mirror mounting loose
          • If the mirror is still on the windshield do not remove. ATTEMPT to fully seat the mirror first. If the mirror is still loose or vibrates, REMOVE and REINSTALL the mirror. REFER to Interior Rear View Mirror in this section. If the condition still exists, INSTALL a new mirror.
           

          Pinpoint Tests

           

          Pinpoint Test D: The Auto-Dimming Mirror Does Not Operate Correctly

          Diagnostic Overview

          Diagnostics in this manual assume a certain skill level and knowledge of Ford-specific diagnostic practices. REFER to Diagnostic Methods in Section 100-00 for more information about these practices.

          Refer to Wiring Diagrams Cell 124 , Power Mirrors for schematic and connector information.

          Normal Operation

          The interior auto-dimming mirror receives voltage from Smart Junction Box (SJB) fuse 41 (15A) through circuit CBP41 (BU) and ground from circuit GD139 (BK/YE). When the selector lever is placed in REVERSE, voltage is sent to circuit CAT03 (GY/BN) from the Body Control Module B (BCM-B) and the interior auto-dimming mirror will turn the dimming feature off. There are 2 photoelectric sensors: one in front of the interior rear view mirror and one mounted on the glass side of the mirror. If the sensors are blocked, the interior mirror auto-dimming feature might not work correctly. Always verify both sensors are not physically blocked before attempting to diagnose auto-dimming mirror concerns.

           
          PINPOINT TEST D: THE AUTO-DIMMING MIRROR DOES NOT OPERATE CORRECTLY
          Test Step Result / Action to Take
            D1 RETRIEVE THE DTCs FROM THE BCM-B  
          • Use the recorded BCM-B DTCs from the continuous and on-demand self tests.
          • Are DTCs retrieved?
          		Yes
          For DTC P0801:11 or P0801:12, GO to D10 . For DTC P0801:13, GO to D11 .

          No
          GO to D2 .
            D2 VERIFY THE FORWARD AND REARWARD FACING SENSORS ARE NOT BLOCKED  
          • Visually 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-OEM window tinting.
          • Were either of the sensors blocked?
          		Yes
          If possible, REMOVE the blockage. TEST the system for normal operation. If it is not possible to remove the blockage, REVIEW the operation of the interior auto-dimming mirror with the customer.

          No
          GO to D3 .
            D3 CHECK OPERATION OF THE INTERIOR AUTO-DIMMING MIRROR — DAYLIGHT CONDITIONS  
          • Ignition ON.
          • Use a bright lamp to illuminate the forward facing sensor and the rearward 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 D4 .

          No
          INSTALL a new interior auto-dimming mirror. REFER to Interior Rear View Mirror in this section. TEST the system for normal operation.
            D4 CHECK THE OPERATION OF THE INTERIOR AUTO-DIMMING MIRROR — NIGHTTIME CONDITIONS WITHOUT GLARE  
          • Ignition ON.
          • NOTE: Covering the sensor with a finger or hand is not adequate.
          • Simulate nighttime conditions without glare:
            • cover the forward sensor with black electrical tape or other dark material.
            • cover 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 D5 .

          No
          GO to D7 .
            D5 CHECK THE OPERATION OF THE INTERIOR AUTO-DIMMING MIRROR — NIGHTTIME CONDITIONS WITH GLARE  
          • Ignition ON.
          • NOTE: Covering the sensor with a finger or hand is not adequate.
          • Simulate nighttime conditions with glare:
            • cover the forward-facing 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 D6 .

          No
          GO to D7 .
            D6 CHECK THE OPERATION OF THE INTERIOR AUTO-DIMMING MIRROR — NIGHTTIME CONDITIONS WITH VEHICLE IN REVERSE  
          • Ignition ON.
          • NOTE: Covering the sensor with a finger or hand is not adequate.
          • Simulate nighttime conditions with glare:
            • cover the forward sensor with black electrical tape or other dark material.
            • illuminate the rearward facing sensor.


          • Select REVERSE.
          • Did the mirror adjust to a high reflectance (clear) mode?
          		Yes
          The system is operating correctly at this time. REVIEW operation of the interior auto-dimming interior mirror feature with the customer.

          No
          GO to D7 .
            D7 CHECK CIRCUIT CBP41 (BU) FOR VOLTAGE  
          • Ignition OFF.
          • Disconnect: Interior Mirror C9039.
          • Start the engine.
          • With the engine running, press the rear window defrost switch on.
          • Measure the voltage between:


            • Positive Lead Negative Lead
            Pin Circuit Pin Circuit
            C9039-1 CBP41 (BU) — Ground



          • Is the voltage greater than 11 volts?
          		Yes
          GO to D8 .

          No
          VERIFY SJB fuse 41 (15A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams manual to identify the possible causes of the circuit short.
            D8 CHECK CIRCUIT GD139 (BK/YE) FOR AN OPEN  
          • Ignition OFF.
          • Measure the resistance between:


            • Positive Lead Negative Lead
            Pin Circuit Pin Circuit
            With Video Display
            C9039-3 GD139 (BK/YE) — Ground
            Without Video Display
            C9039-4 GD139 (BK/YE) — Ground



          • Is the resistance less than 3 ohms?
          		Yes
          GO to D9 .

          No
          REPAIR the circuit.
            D9 CHECK THE REVERSE INHIBIT CONTROL CIRCUIT FOR VOLTAGE  
          • Ignition ON.
          • Select REVERSE.
          • Measure the voltage between:


            • Positive Lead Negative Lead
            Pin Circuit Pin Circuit
            With Video Display
            C9039-2 CAT03 (GY/BN) — Ground
            With Compass
            C9039-3 CAT03 (GY/BN) — Ground
            Without Video Display and Compass
            C9039-9 CAT03 (GY/BN) — Ground



          • Is the voltage greater than 11 volts?
          		Yes
          INSTALL a new interior auto-dimming mirror. REFER to Interior Rear View Mirror in this section.

          No
          GO to D11 .
            D10 CHECK FOR DTCs IN THE BCM-B WITH THE INTERIOR MIRROR DISCONNECTED  
          • Disconnect: Interior Mirror C9039.
          • Ignition ON.
          • Clear any DTCs stored in the BCM-B .
          • NOTE: DTC P0801:13 may return during this step due to the interior mirror being disconnected.
          • Perform the BCM-B self test.
          • Is DTC B0801:11 or B0801:12 present?
          		Yes
          For DTC P0801:11, GO to D12 . For DTC P0801:12, GO to D13 .

          No
          INSTALL a new interior mirror. REFER to Interior Rear View Mirror in this section.
            D11 CHECK THE REVERSE INHIBIT CONTROL CIRCUIT FOR AN OPEN  
          • Ignition OFF.
          • Disconnect: Interior Mirror C9039.
          • Disconnect: BCM-B C4368A.
          • Measure the resistance between:


            • Positive Lead Negative Lead
            Pin Circuit Pin Circuit
            With Video Display
            C4368A-6 CAT03 (GY/BN) C9039-2 CAT03 (GY/BN)
            With Compass
            C4368A-6 CAT03 (GY/BN) C9039-3 CAT03 (GY/BN)
            Without Video Display and Compass
            C4368A-6 CAT03 (GY/BN) C9039-9 CAT03 (GY/BN)



          • Is the resistance less than 3 ohms?
          		Yes
          GO to D14 .

          No
          REPAIR the circuit.
            D12 CHECK THE REVERSE INHIBIT CONTROL CIRCUIT FOR A SHORT TO GROUND  
          • Ignition OFF.
          • Disconnect: BCM-B C4368A.
          • Measure the resistance between:


            • Positive Lead Negative Lead
            Pin Circuit Pin Circuit
            C4368A-6 CAT03 (GY/BN) — Ground



          • Is the resistance greater than 10,000 ohms?
          		Yes
          REPAIR the circuit.

          No
          GO to D14 .
            D13 CHECK THE REVERSE INHIBIT CONTROL CIRCUIT FOR A SHORT TO VOLTAGE  
          • Ignition OFF.
          • Disconnect: BCM-B C4368A.
          • Ignition ON.
          • Measure the voltage between:


            • Positive Lead Negative Lead
            Pin Circuit Pin Circuit
            C4368-6 CAT03 (GY/BN) — Ground



          • Is any voltage present?
          		Yes
          REPAIR the circuit.

          No
          GO to D14 .
            D14 CHECK FOR CORRECT BCM-B OPERATION  
          • Disconnect all BCM-B connectors.
          • Check for:
            • corrosion.
            • pushed-out pins.
          • Connect all BCM-B connectors and make sure they seat correctly.
          • Operate the system and verify the concern is still present.
          • Is the concern still present?
          		Yes
          INSTALL a new BCM-B . REFER to Section 419-10 .

          No
          The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector.