Pinpoint Test AA: The Fog Lamps Are On Continuously

Fog Lamps

Pinpoint Test AA: The Fog Lamps Are On Continuously

Refer to Wiring Diagram Set 86, Fog Lamps for schematic and connector information Electrical Diagrams.

Normal Operation

The Front Lighting Control Module (FLM) monitors the fog lamp switch. When the fog lamp switch is pressed, the FLM (Front Lighting Control Module) sends a message over the High Speed Controller Area Network (HS-CAN) to the Body Control Module (BCM) to indicate the fog lamp request. When the BCM (Body Control Module) receives input from the FLM (Front Lighting Control Module) indicating a request for the fog lamps, the BCM (Body Control Module) provides ground to the fog lamp relay (integrated into the BCM (Body Control Module)). When the fog lamp relay is energized, voltage is routed to the fog lamps.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Headlamp switch (integrated into the FLM (Front Lighting Control Module))

- BCM (Body Control Module)

PINPOINT TEST AA : THE FOG LAMPS ARE ON CONTINUOUSLY

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

AA1 CHECK THE FOG LAMP SWITCH PID

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: FLM (Front Lighting Control Module) DataLogger.

- Monitor the FLM (Front Lighting Control Module) fog lamp switch PID (FOG_F_SW) while pressing and releasing the fog lamp switch.

Does the PID indicate the fog lamp switch is active when pressed and inactive when released?

Yes
GO to AA2.

No
INSTALL a new FLM (Front Lighting Control Module). REFER to Front Lighting Control Module (FLM) . TEST the system for normal operation.

AA2 CHECK THE BCM (Body Control Module) FOG LAMP OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE

- Ignition OFF.

- Disconnect: BCM (Body Control Module) C2280E.

- Ignition ON.

Do the fog lamps continue to illuminate?

Yes
REPAIR circuit CLF12 (BN/YE) for a short to voltage. TEST the system for normal operation.

No
GO to AA3.

AA3 CHECK FOR CORRECT BCM (Body Control Module) OPERATION

- Ignition OFF.

- 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.