Pinpoint Test AQ: The Compass Is Inoperative (Without Navigation)

WARNING: This page is about a different car, the 2012 Ford Pickup, 2012 Ford F550 Super Duty, 2012 Ford F450 Super Duty, and 2012 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTE: Failure to disconnect the battery when instructed results in false resistance readings. Refer to BATTERY, MOUNTING AND CABLES .

AQ1 CHECK THE AUTO-DIMMING INTERIOR MIRROR VOLTAGE SUPPLY
- Ignition OFF.
- Disconnect: Auto-Dimming Interior Mirror C911.
- Ignition ON.
- Measure the voltage between the auto-dimming interior mirror C911-1, circuit CBP32 (GN/VT), harness side and ground.
  
  Fig 1: Measuring Voltage Between Auto-Dimming Interior Mirror C911-1, Circuit CBP32 (GN/VT), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to AQ2.
- No : VERIFY the BCM fuse 32 (15A). If OK, REPAIR circuit CBP32 (GN/VT) for an open. TEST the system for normal operation. If not OK, REFER to the appropriate SYSTEM WIRING DIAGRAMS article to identify the possible causes of the circuit short.
AQ2 CHECK THE COMPASS MODULE GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the auto-dimming interior mirror C911-4, circuit GD133 (BK), harness side and ground.
  
  Fig 2: Measuring Resistance Between Auto-Dimming Interior Mirror C911-4, Circuit GD133 (BK), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to AQ3.
- No : REPAIR circuit GD133 (BK) for an open. CLEAR the DTCs. REPEAT the self-test.
AQ3 CHECK THE COMPASS COMMUNICATION BUS FOR A SHORT TO VOLTAGE
- Connect: Negative Battery Cable.
- Disconnect: DC/AC Inverter Module C3501A.
- Disconnect: BCM C2280B.
- Ignition ON.
- Measure the voltage between the auto-dimming interior mirror C911-2, circuit VDM01 (BU/WH), harness side and ground.
  
  Fig 3: Measuring Voltage Between Auto-Dimming Interior Mirror C911-2, Circuit VDM01 (BU/WH), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
- Yes : REPAIR circuit VDM01 (BU/WH) for a short to voltage. CLEAR the DTCs. REPEAT the self-test.
- No : GO to AQ4.
AQ4 CHECK THE COMPASS COMMUNICATION BUS FOR AN OPEN AND SHORT TO GROUND
- Disconnect: BCM C2280B.
- Measure the resistance between the BCM C2280B-52, circuit VDN01 (BU/WH), harness side and the auto-dimming interior mirror C911-2, circuit VDM01 (BU/WH), harness side; and between the BCM C2280B-52, circuit VDN01 (BU/WH), and ground.
  
  Fig 4: Checking Compass Communication Bus For Open And Short To Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms between the BCM and the auto-dimming interior mirror, and greater than 10, 000 ohms between the BCM and ground?
- Yes : INSTALL a new auto-dimming interior mirror. REFER to REAR VIEW MIRRORS . SET the zone. REFER to COMPASS ZONE ADJUSTMENT . CALIBRATE the compass. REFER to COMPASS CALIBRATION . CLEAR the DTCs. REPEAT the self-test.
  If the compass is still inoperative, GO to AQ5.
- No : REPAIR circuit VDM01 (BU/WH) for an open or short to ground. CLEAR the DTCs. REPEAT the self-test.
AQ5 CHECK FOR CORRECT BCM OPERATION
- Disconnect all the BCM connectors.
- Check for:
  - corrosion
  - damaged pins
  - pushed-out pins
- Connect all the BCM 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. REFER to MULTIFUNCTION ELECTRONIC MODULES . TEST the system for normal operation.
- No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.