Pinpoint Test N: The Autolamps Are Inoperative

Autolamps

Pinpoint Test N: The Autolamps Are Inoperative

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

Normal Operation

The Front Lighting Control Module (FLM) sends the status of the headlamp switch position to the Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN).

The autolamps feature is enabled when the BCM (Body Control Module) receives a message from the FLM (Front Lighting Control Module) indicating the headlamp switch is in the AUTOLAMPS ON position.

When the BCM (Body Control Module) enables the autolamps feature, the BCM (Body Control Module) monitors the light sensor input. The light sensor determines the amount of light based on the input received from the ambient lighting conditions. When the ambient level has reached a point determined by the internal programming of the BCM (Body Control Module), the BCM (Body Control Module) provides voltage to the exterior lamps.

Any fault detected from the light sensor or headlamp switch inputs causes the exterior lamps to illuminate.

This pinpoint test is intended to diagnose the following:

- Light sensor

- BCM (Body Control Module)

PINPOINT TEST N : 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.

N1 CHECK THE MANUAL HEADLAMP OPERATION

- Place the headlamp switch in the HEADLAMPS ON and OFF positions.

Do the headlamps operate correctly?

Yes
GO to N2.

No
REFER to Headlamps Special Tool(s) Used With Diagnostics.

N2 CHECK FOR VOLTAGE TO THE LIGHT SENSOR

- Ignition OFF.

- Disconnect: Light Sensor C287 (Manual Temperature Control) or C286 (Automatic Temperature Control).

- 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.






- For vehicles with manual temperature control, measure the voltage between the light sensor C287-A, circuit VLF14 (BU/BN), harness side and ground.






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 N3.

N3 CHECK FOR CORRECT BCM (Body Control Module) OPERATION

- Disconnect all the BCM (Body Control Module) connectors.

- Check for:
- corrosion

- damaged pins

- pushed-out pins


- Connect all the BCM (Body Control Module) 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 (Body Control Module). 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.