Pinpoint Test Q: Both Fog Lamps Are Inoperative
Fog Lamps
Pinpoint Tests
Pinpoint Test Q: Both Fog Lamps Are 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) monitors the fog lamp switch position by sending a voltage signal to the headlamp switch. When the fog lamp switch is engaged, the voltage signal is routed to ground indicating a request for the fog lamps.
The 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. The fog lamps share a common ground circuit.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Headlamp switch
- SCCM
- BCM
PINPOINT TEST Q: BOTH FOG LAMPS 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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Q1 CHECK THE FOG LAMP SWITCH PID
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SCCM DataLogger.
- Monitor the SCCM fog lamp switch PID while engaging the fog lamp switch.
- Does the PID indicate the fog lamp switch is on?
Yes
VERIFY the BCM fuse 47 (15A) is OK. If OK, GO to Q4. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
No
GO to Q2.
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Q2 CHECK FOR A VOLTAGE SIGNAL TO THE HEADLAMP SWITCH
- Ignition OFF.
- Disconnect: Headlamp Switch C205 .
- Measure the voltage between the headlamp switch C205-5, circuit CLF21 (GY/VT), harness side and ground.
- Is the voltage approximately 5 volts?
Yes
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. TEST the system for normal operation.
No
GO to Q3.
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Q3 CHECK THE FOG LAMP REQUEST INPUT CIRCUIT FOR AN OPEN
- Disconnect: SCCM C2414a .
- Measure the resistance between the headlamp switch C205-5, circuit CLF21 (GY/VT), harness side and the SCCM C2414a-1, circuit CLF21 (GY/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to Q6.
No
REPAIR circuit CLF21 (GY/VT) for an open. TEST the system for normal operation.
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Q4 BYPASS THE BCM
NOTE: If the fuse in the jumper wire fails, refer to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
- Ignition OFF.
- Disconnect: BCM C2280e .
- Connect a fused jumper wire between the BCM C2280e-5, circuit CLF12 (BN/YE), harness side and battery positive.
- Do the fog lamps illuminate?
Yes
REMOVE the jumper wire. GO to Q7.
No
LEAVE the jumper wire connected. GO to Q5.
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Q5 CHECK FOR VOLTAGE TO THE FOG LAMP
- Disconnect: LH Fog Lamp C152 .
- Measure the voltage between the LH fog lamp C152-A, circuit CLF12 (BN/YE), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
REMOVE the jumper wire. REPAIR circuit GD122 (BK) for an open. TEST the system for normal operation.
No
REMOVE the jumper wire. REPAIR circuit CLF12 (BN/YE) for an open. TEST the system for normal operation.
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Q6 CHECK FOR CORRECT SCCM OPERATION
- Disconnect all the SCCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SCCM 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 SCCM. REFER to Steering Column Switches Service and Repair. 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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Q7 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 BCM. REFER to Multifunction Electronic Modules Service and Repair. 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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