Pinpoint Test R: Both Fog Lamps Are Inoperative
Fog Lamps
Pinpoint Tests
Pinpoint Test R: Both Fog Lamps Are Inoperative
Refer to Wiring Diagram Set 86, Fog Lamps for schematic and connector information. Diagrams By Number
Normal Operation
The Lighting Control Module (LCM) sends a voltage reference signal to the headlamp switch. When the fog lamp switch is engaged, the signal is routed to ground. When a request for the fog lamps is detected (and the exterior lamps are on), the LCM provides voltage to the fog lamp relay coil, energizing the fog lamp relay. Voltage for the fog lamp relay is provided by the Battery Junction Box (BJB). When the fog lamp relay is energized, voltage is routed to the fog lamps.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Fog lamp relay
- Headlamp switch
- LCM
PINPOINT TEST R: 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.
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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R1 MONITOR THE LCM HEADLAMP SWITCH PID
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: LCM DataLogger.
- Monitor the LCM headlamp switch status PID (HD_LMP_SW) while placing the headlamp switch in the PARKING LAMPS ON position and engaging the fog lamp switch.
- Does the headlamp switch PID indicate the fog lamp switch is active?
Yes
GO to R2.
No
GO to R7.
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R2 CHECK THE FOG LAMP RELAY
- Place the headlamp switch in the OFF position.
- Ignition OFF.
- Disconnect: Fog Lamp Relay.
- Carry out the fog lamp relay component test.
- Is the fog lamp relay OK?
Yes
GO to R3.
No
INSTALL a new fog lamp relay. TEST the system for normal operation.
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R3 CHECK FOR VOLTAGE TO THE FOG LAMP RELAY
- Ignition OFF.
- Measure the voltage between the fog lamp relay pin 3, circuit 1669 (OG/LG), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to R4.
No
VERIFY the BJB fuse 15 (15A) is OK. If OK, REPAIR circuit 1669 (OG/LG) for an open. TEST the system for normal operation. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. Diagrams By Number
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R4 BYPASS THE FOG LAMP RELAY
- Connect a fused jumper wire between the fog lamp relay pin 3, circuit 1669 (OG/LG), BJB face side and the fog lamp relay pin 5, circuit 478 (TN/OG), BJB face side.
- Do the fog lamps illuminate?
Yes
REMOVE the jumper wire. GO to R5.
No
REMOVE the jumper wire. REPAIR circuit 478 (TN/OG) for an open. TEST the system for normal operation.
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R5 CHECK THE FOG LAMP RELAY GROUND CIRCUIT FOR AN OPEN
- Disconnect: Negative Battery Cable.
- Measure the resistance between the fog lamp relay pin 2, circuit 57 (BK), BJB face side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to R6.
No
REPAIR circuit 57 (BK) for an open. TEST the system for normal operation.
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R6 CHECK THE FOG LAMP RELAY COIL CIRCUIT FOR AN OPEN AND SHORT TO GROUND
- Disconnect: LCM C2145b.
- Measure the resistance between the fog lamp relay pin 1, circuit 1347 (DB/WH), BJB face side and the LCM C2145a-12, circuit 1347 (DB/WH), harness side; and between the fog lamp relay pin 1, circuit 1347 (DB/WH), BJB face side and ground.
- Is the resistance less than 5 ohms between the fog lamp relay and the LCM, and greater than 10,000 ohms between the fog lamp relay and ground?
Yes
GO to R9.
No
REPAIR circuit 1347 (DB/WH) as necessary. TEST the system for normal operation.
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R7 CHECK THE HEADLAMP SWITCH INPUT
- Place the headlamp switch in the OFF position.
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: LCM C2145b.
- Place the headlamp switch in the PARKING LAMPS ON position and engage the fog lamp switch.
- Measure the resistance between the LCM C2145b-11, circuit 477 (LB/BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to R9.
No
GO to R8.
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R8 CHECK THE FOG LAMP REQUEST INPUT CIRCUIT FOR AN OPEN
- Disconnect: Headlamp Switch C205a.
- Measure the resistance between the LCM C2145b-11, circuit 477 (LB/BK), harness side and the headlamp switch C205a-6, circuit 477 (LB/BK), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. TEST the system for normal operation.
No
REPAIR circuit 477 (LB/BK) for an open. TEST the system for normal operation.
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R9 CHECK FOR CORRECT LCM OPERATION
- Ignition OFF.
- 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. REFER to Body Control Systems. 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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