Pinpoint Test F: The Autolamps Are Inoperative

Autolamps

Pinpoint Test F: The Autolamps Are Inoperative

Refer to Wiring Diagram Set 85, Headlamps/Autolamps for schematic and connector information. Diagrams By Number

Normal Operation

When a request for the autolamps is detected by the Lighting Control Module (LCM), the LCM sends a voltage reference signal to the light sensor through circuit 218 (WH/VT). The light sensor is provided ground through circuit 676 (PK/OG). When high ambient light conditions exist, the light sensor pulls the voltage signal low. When low ambient light conditions exist, the voltage signal to the light sensor is read high by the LCM. Based on input from the light sensor, the LCM determines when to supply voltage to the exterior lamps.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Light sensor
- LCM



PINPOINT TEST F: THE AUTOLAMPS ARE INOPERATIVE

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

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F1 CHECK THE MANUAL HEADLAMP AND PARKING LAMP OPERATION


- Place the headlamp switch in the HEADLAMPS ON position.
- Do the headlamps and parking lamps operate correctly?

Yes
GO to F2.

No
REFER to Headlamps or Parking, Rear and License Plate Lamps Testing and Inspection.

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F2 CHECK FOR VOLTAGE TO THE LIGHT SENSOR


- Disconnect: Light Sensor C287.
- Ignition ON.
- Place the headlamp switch in the AUTOLAMPS ON position.
- Measure the voltage between the light sensor C287-2, circuit 218 (WH/VT), harness side and ground.




- Is the voltage approximately 5 volts?

Yes
INSTALL a new light sensor. REFER to Light Sensor Service and Repair. TEST the system for normal operation.

No
GO to F3.

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F3 CHECK CIRCUIT 218 (WH/VT) FOR A SHORT TO GROUND


- Ignition OFF.
- Disconnect: LCM C2145a.
- Measure the resistance between the light sensor C287-2, circuit 218 (WH/VT), harness side and ground.




- Is the resistance greater than 10,000 ohms?

Yes
GO to F4.

No
REPAIR the circuit. TEST the system for normal operation.

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F4 CHECK FOR CORRECT LCM OPERATION


- Disconnect all the LCM connectors.
- Check for:
- corrosion
- damaged pins
- 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. 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.

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