Pinpoint Test W: The Front/Rear Fog Lamp Indicator Is Never/Always On
Instrumentation and Warning Chimes
Pinpoint Tests
Pinpoint Test W: The Front/Rear Fog Lamp Indicator Is Never/Always On
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information. Diagrams By Number
Normal Operation
The Instrument Cluster (IC) receives the front and rear fog lamp on/off status from the Generic Electronic Module (GEM) over the Medium Speed Controller Area Network (MS-CAN) communication bus. The GEM is hardwired to the headlamp switch. When the front or rear fog lamps are on, the headlamp switch provides voltage to the fog lamps and the GEM. The GEM monitors the voltage input on the fog lamp input circuit and sends a message to the IC to turn on the front or rear fog lamp indicator.
If the fog lamp data is missing for less than 5 seconds, the front or rear fog lamp indicator remains in the last indication mode (on or off), based upon the last known good data message. If the fog lamp data is missing for more than 5 seconds, the IC defaults the front or rear fog lamp indicator off.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Front fog lamp concern
- Rear fog lamp concern
- GEM
- IC
PINPOINT TEST W: THE FRONT/REAR FOG LAMP INDICATOR IS NEVER/ALWAYS ON
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W1 CHECK THE INOPERATIVE FOG LAMP CONCERN
- Operate the front and rear fog lamps while monitoring the fog lamp indicator in the IC.
- Is the front fog lamp indicator inoperative?
Yes
GO to W2.
No
GO to W5.
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W2 CARRY OUT THE IC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC front fog lamp (F_FOG_LMP) active command. Command the front fog lamp indicator on and off while observing the front fog lamp indicator.
- Does the front fog lamp indicator illuminate when commanded on, and turn off when commanded off?
Yes
GO to W3.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Service and Repair. TEST the system for normal operation.
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W3 CHECK THE FRONT FOG LAMP OPERATION
- Turn on the front fog lamps while monitoring the front fog lamps.
- Do the front fog lamps operate?
Yes
GO to W4.
No
REFER to Exterior Lighting Testing and Inspection.
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W4 CHECK THE FRONT FOG LAMP INPUT TO THE GEM
- Turn the front fog lamps off.
- Ignition OFF.
- Disconnect: GEM C201b.
- Turn the front fog lamps on.
- Measure the voltage between the GEM C201b-20, circuit 15S-LD7 (GN/BU), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to W8.
No
REPAIR circuit 15S-LD7 (GN/BU) for an open. TEST the system for normal operation.
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W5 CARRY OUT THE IC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger.
- Select the IC rear fog lamp (R_FOG_LMP) active command. Command the rear fog lamp indicator on and off while observing the rear fog lamp indicator.
- Does the rear fog lamp indicator illuminate when commanded on, and turn off when commanded off?
Yes
GO to W6.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Service and Repair. TEST the system for normal operation.
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W6 CHECK THE REAR FOG LAMP OPERATION
- Turn on the rear fog lamps while monitoring the rear fog lamps.
- Do the rear fog lamps operate?
Yes
GO to W7.
No
REFER to Exterior Lighting Testing and Inspection.
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W7 CHECK THE REAR FOG LAMP INPUT TO THE GEM
- Turn the rear fog lamps off.
- Ignition OFF.
- Disconnect: GEM C201b.
- Turn the rear fog lamps on.
- Measure the voltage between the GEM C201b-19, circuit 15S-LD13 (GN/OG), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to W8.
No
REPAIR circuit 15S-LD13 (GN/OG) for an open. TEST the system for normal operation.
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W8 CHECK FOR CORRECT GEM OPERATION
- Disconnect the GEM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the GEM 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 GEM. 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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