Pinpoint Test T: The Fog Lamps On Indicator Is Inoperative

Fog Lamps

Pinpoint Tests

Pinpoint Test T: The Fog Lamps On Indicator Is Inoperative

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

Normal Operation

The Steering Column Control Module (SCCM) sends a message over the High Speed Controller Area Network (HS-CAN) to the Body Control Module (BCM) to indicate the fog lamp switch position. When the BCM receives input from the SCCM indicating a request for the fog lamps, the BCM provides ground to the fog lamp relay (integrated into the BCM). When the fog lamp relay is energized, voltage is routed to the fog lamps and on a separate circuit, to the headlamp switch for the fog lamps on indicator.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors
- Headlamp switch
- BCM

PINPOINT TEST T: THE FOG LAMPS ON INDICATOR IS 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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T1 CHECK THE HEADLAMP SWITCH

- Ignition OFF.
- Disconnect: Headlamp Switch C205 .
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: BCM DataLogger.
- Select the BCM fog lamps active command PID (FOG_LAMPS). Command the fog lamps on.

- NOTE: Make sure the fog lamps are illuminated when taking a reading.

- Measure the voltage between the headlamp switch C205-10, circuit CLF12 (BN/YE), harness side and ground.




- Is the voltage greater than 10 volts?

Yes
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. TEST the system for normal operation.

No
GO to T2.

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T2 CHECK THE BCM FOG LAMP INDICATOR OUTPUT CIRCUIT FOR AN OPEN

- Ignition OFF.
- Disconnect: BCM C2280a .
- Measure the resistance between the headlamp switch C205-10, circuit CLF12 (BN/YE), harness side and the BCM C2280a-2, circuit CLF12 (BN/YE), harness side.




- Is the resistance less than 5 ohms?

Yes
GO to T3.

No
REPAIR circuit CLF12 (BN/YE) for an open. TEST the system for normal operation.

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T3 CHECK FOR CORRECT BCM OPERATION

- Disconnect all the BCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM 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. 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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