Pinpoint Test T: The Fog Lamps Are On Continuously
Fog Lamps
Pinpoint Tests
Pinpoint Test T: The Fog Lamps Are On Continuously
Refer to Wiring Diagram Set 86, Fog Lamps for schematic and connector information. Diagrams By Number
Normal Operation
The Smart Junction Box (SJB) sends a reference signal to the headlamp switch through circuit CLF21 (GY/VT) to monitor the fog lamp request. When the fog lamp switch is engaged, the voltage signal is routed to ground.
When the SJB detects the fog lamps on request, the SJB provides ground to the fog lamp relay coil (integrated into the SJB). When the fog lamp relay is energized, voltage is routed through circuit CLF12 (BN/YE) to the fog lamps and to the headlamp switch for the fog lamps on indicator.
- DTC B2254 (Front Fog Lamp Switch Failure) - an on-demand DTC that sets when the SJB detects a short to ground from the fog lamp switch input circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp switch
- SJB
PINPOINT TEST T: 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.
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T1 CHECK FOR RECORDED SJB DTCs
- Check the recorded results from the SJB self-test.
- Is DTC B2254 present?
Yes
GO to T2.
No
GO to T4.
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T2 CHECK THE HEADLAMP SWITCH
- Ignition OFF.
- Disconnect: Headlamp Switch C205.
- Carry out the headlamp switch component test.
- Is the headlamp switch OK?
Yes
GO to T3.
No
INSTALL a new headlamp switch. REFER to Headlamp Switch Service and Repair. CLEAR the DTCs. REPEAT the self-test.
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T3 CHECK THE FOG LAMPS ON REQUEST INPUT CIRCUIT FOR A SHORT TO GROUND
- Disconnect: SJB C2280b.
- Measure the resistance between the headlamp switch C205-6, circuit CLF21 (GY/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to T6.
No
REPAIR circuit CLF21 (GY/VT) for a short to ground. CLEAR the DTCs. REPEAT the self-test.
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T4 CHECK THE SJB FOG LAMPS OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE (TO HEADLAMP SWITCH)
- Ignition OFF.
- Disconnect: SJB C2280a.
- Ignition ON.
- Do the fog lamps continue to illuminate?
Yes
GO to T5.
No
REPAIR circuit CLF12 (BN/YE) for a short to voltage. TEST the system for normal operation.
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T5 CHECK THE SJB FOG LAMPS OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE (TO THE FOG LAMPS)
- Ignition OFF.
- Disconnect: SJB 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 T6.
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T6 CHECK FOR CORRECT SJB OPERATION
- Ignition OFF.
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB 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. CLEAR any DTCs. REPEAT the self-test.
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