Pinpoint Test U: The Fog Lamps Are On Continuously
Fog Lamps
Pinpoint Test U: The Fog Lamps Are On Continuously
Refer to Wiring Diagram Set 86, Fog Lamps for schematic and connector information. [1][2]Diagrams By Number
Normal Operation
The Smart Junction Box (SJB) sends a voltage signal to the headlamp switch to monitor the fog lamp request. When the fog lamp switch is engaged, the voltage signal is routed to ground.
When the SJB (Smart Junction Box) detects the fog lamps on request, the SJB (Smart Junction Box) energizes the fog lamp relay (integrated into the SJB (Smart Junction Box)). When the fog lamp relay is energized, voltage is routed through 2 output circuits from the SJB (Smart Junction Box). One output is to the fog lamps and the other output is 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 (Smart Junction Box) detects a short to ground from the fog lamp on input circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp switch
- SJB (Smart Junction Box)
PINPOINT TEST U : 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.
U1 CHECK FOR RECORDED SJB (Smart Junction Box) DTCs
- Check the recorded results from the SJB (Smart Junction Box) self-test.
Is DTC B2254 present?
Yes
GO to U2.
No
GO to U4.
U2 CHECK THE HEADLAMP SWITCH
- Ignition OFF.
- Disconnect: Headlamp Switch C205.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB (Smart Junction Box) Self-Test.
- NOTE: Other DTCs will be present with the headlamp switch disconnected and should be ignored.
Repeat the SJB (Smart Junction Box) self-test.
Is DTC B2254 still present?
Yes
GO to U3.
No
INSTALL a new headlamp switch. REFER to Headlamp Switch . CLEAR the DTCs. REPEAT the self-test.
U3 CHECK THE FOG LAMPS ON REQUEST INPUT CIRCUIT FOR A SHORT TO GROUND
- Disconnect: SJB (Smart Junction Box) C2280B.
- Measure the resistance between the headlamp switch C205-5, circuit CLF21 (GY/VT), harness side and ground.
Is the resistance greater than 10,000 ohms?
Yes
GO to U6.
No
REPAIR circuit CLF21 (GY/VT) for a short to ground. CLEAR the DTCs. REPEAT the self-test.
U4 CHECK THE SJB (Smart Junction Box) FOG LAMPS OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE (TO HEADLAMP SWITCH)
- Ignition OFF.
- Disconnect: SJB (Smart Junction Box) C2280A.
- Ignition ON.
Do the fog lamps continue to illuminate?
Yes
GO to U5.
No
REPAIR circuit CLF12 (BN/YE) to the headlamp switch for a short to voltage. TEST the system for normal operation.
U5 CHECK THE SJB (Smart Junction Box) FOG LAMPS OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE (TO THE FOG LAMPS)
- Ignition OFF.
- Disconnect: SJB (Smart Junction Box) 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 U6.
U6 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION
- Ignition OFF.
- Disconnect all the SJB (Smart Junction Box) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB (Smart Junction Box) 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 (Smart Junction Box). 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.