Pinpoint Test G: The AUTOLAMPS Are Inoperative

WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. 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.

G1 CHECK THE MANUAL HEADLAMP OPERATION
- Place the headlamp switch in the HEADLAMPS ON position.
- Do the headlamps operate correctly?
- Yes: GO to G2 .
- No: REFER to HEADLAMPS .
G2 CHECK FOR VOLTAGE TO THE LIGHT SENSOR
- Ignition OFF.
- Disconnect: Light Sensor C286 or C287.
- Ignition ON.
- Place the headlamp switch in the AUTOLAMPS ON position.
- For vehicles with automatic temperature control, measure the voltage between the light sensor C286-2, circuit VLF14 (BU/BN), harness side and ground.
  
  Fig 1: Measuring Voltage Between Light Sensor C286-2, Circuit VLF14 (BU/BN), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- For vehicles with manual temperature control, measure the voltage between the light sensor C287-A, circuit VLF14 (BU/BN), harness side and ground.
  
  Fig 2: Measuring Voltage Between Light Sensor C287-A, Circuit VLF14 (BU/BN), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage approximately 5 volts?
- Yes: INSTALL a new light sensor. REFER to LIGHT SENSOR . TEST the system for normal operation.
- No: GO to G3 .
G3 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
  - corrosion
  - damaged pins
  - pushed-out pins
- Connect all the SJB 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 SJB . 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.