Pinpoint Test AL: The Compass Is Inoperative

WARNING: This page is about a different car, the 2004 Mercury Monterey and 2004 Ford Freestar. However, it is still accessible from the selected car via links, so may be relevant.

AL1 CHECK CIRCUIT 1040 (RD/BK) FOR BATTERY VOLTAGE
- Key in OFF position.
- Disconnect: Overhead Console C930.
- Key in ON position.
- Measure the voltage between the overhead console C930-3, circuit 1040 (RD/BK), harness side and ground.
  
  Fig 1: Measuring Voltage Between Overhead Console C930-3, Circuit 1040 (RD/BK), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes

GO to AL2

No

REPAIR the circuit. TEST the system for normal operation.
AL2 CHECK CIRCUIT 1203 (BK/LB) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the overhead console C930-4, circuit 1203 (BK/LB), harness side and ground.
  
  Fig 2: Measuring Resistance Between Overhead Console C930-4, Circuit 1203 (BK/LB), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes

GO to AL3

No

REPAIR the circuit. TEST the system for normal operation.
AL3 CHECK CIRCUIT 702 (WH/BK) AND CIRCUIT 703 (WH/OG) FOR OPEN AND SHORT TO GROUND
- Disconnect: Instrument Cluster C220a.
- Measure the resistance between the overhead console C930-15, circuit 703 (WH/OG), harness side and the instrument cluster C220a-14, circuit 703 (WH/OG), harness side; and between the overhead console C930-15, circuit 703 (WH/OG), harness side and ground.
Fig 3: Checking Circuit 702 (WH/BK) And Circuit 703 (WH/OG) For Open And Short To Ground (1 Of 2)
Courtesy of FORD MOTOR CO.
Measure the resistance between the overhead console C930-5, circuit 702 (WH/BK), harness side and the instrument cluster C220a-15, circuit 702 (WH/BK), harness side; and between the overhead console C930-5, circuit 702 (WH/BK), harness side and ground.

Fig 4: Checking Circuit 702 (WH/BK) And Circuit 703 (WH/OG) For Open And Short To Ground (2 Of 2)
Courtesy of FORD MOTOR CO.
Are the resistances less than 5 ohms between the compass sensor module and the instrument cluster; and greater than 10,000 ohms between the compass sensor module and ground?

Yes

INSTALL a new compass sensor module. SET the zone. Refer to COMPASS ZONE ADJUSTMENT . CALIBRATE the compass. Refer to COMPASS CALIBRATION . TEST the system for normal operation.

REPAIR the circuit(s) in question. TEST the system for normal operation.