Pinpoint Test B: The Alarm System Does Not Disarm - Using The Driver Door Disarm Switch

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

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

B1 CHECK THE DRIVER DOOR DISARM SWITCH FOR DISARMING OPERATION
- Enter the following diagnostic mode on the diagnostic tool: LCM PID.
- Monitor the LCM driver door disarm switch PID.
- Does the LCM driver door disarm switch PID agree with the switch position?
Yes : The anti-theft system is operating correctly. CLARIFY the concern with the customer.

No : GO to B2.
B2 CHECK CIRCUIT 25 (DG/VT) FOR AN OPEN
- Key in OFF position.
- Disconnect: LCM C2145b.
- Disconnect: Driver Door Perimeter Disarm Switch C579.
- Measure the resistance between the LCM C2145b-9, circuit 25 (DG/VT), harness side and the driver door perimeter disarm switch C579-2, circuit 25 (DG/VT), harness side.
  
  Fig 1: Measuring Resistance Between LCM C2145B-9 Circuit 25 And Driver Door Perimeter Disarm Switch C579-2 Circuit 25
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to B3.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
B3 CHECK CIRCUIT 25 (DG/VT) FOR AN OPEN
- Measure the resistance between the LCM C2145b-9, circuit 25 (DG/VT), harness side and ground.
  
  Fig 2: Measuring Resistance Between LCM C2145B-9 Circuit 25 Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to B4.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
B4 CHECK CIRCUIT 57 (BK) FOR AN OPEN
- Measure the resistance between the driver door perimeter disarm switch C579-3, circuit 57 (BK), harness side and ground.
  
  Fig 3: Measuring Resistance Between Driver Door Perimeter Disarm Switch C579-3 Circuit 57 (Be) Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to B5.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
B5 CHECK DRIVER DOOR PERIMETER DISARM SWITCH FOR CORRECT OPERATION
- While toggling the switch, measure the resistance between the driver door perimeter disarm switch pin 2 and pin 3, component side.
  
  Fig 4: Measuring Resistance Between Driver Door Perimeter Disarm Switch Pin 2 And Pin 3
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to B6.

No : INSTALL a new driver door disarm switch. REFER to DOOR DISARM SWITCH . CLEAR the DTCs. REPEAT the self-test.
B6 CHECK FOR CORRECT LCM OPERATION
- Disconnect all the LCM connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all the LCM 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 LCM. REFER to MULTIFUNCTION ELECTRONIC MODULES . CLEAR the DTCs. REPEAT the self-test.

No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.