Pinpoint Test S: Both Fog Lamps Are Inoperative

Fog Lamps

Pinpoint Test S: Both Fog Lamps Are Inoperative

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 to the fog lamps.

This pinpoint test is intended to diagnose the following:

- Fuse

- Wiring, terminals or connectors

- Headlamp switch

- SJB (Smart Junction Box)

PINPOINT TEST S : 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.

S1 CHECK THE SJB (Smart Junction Box) FOG LAMP SWITCH PID

- Ignition ON.

- Enter the following diagnostic mode on the scan tool: SJB (Smart Junction Box) Data Logger.

- Monitor the SJB (Smart Junction Box) fog lamp PID (FOG SW) while engaging the fog lamp switch.

Does the PID indicate the fog lamp switch is on?

Yes
VERIFY the SJB (Smart Junction Box) fuse 21 (15A) is OK. If OK, GO to S4. If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. [1][2]Diagrams By Number

No
GO to S2.

S2 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.





- Ignition ON.

Is the voltage greater than 10 volts?

Yes
INSTALL a new headlamp switch. REFER to Headlamp Switch . TEST the system for normal operation.

No
GO to S3.

S3 CHECK THE FOG LAMPS ON REQUEST INPUT CIRCUIT FOR AN OPEN

- Ignition OFF.

- Disconnect: SJB (Smart Junction Box) C2280B.

- Measure the resistance between the headlamp switch C205-5, circuit CLF21 (GY/VT), harness side and the SJB (Smart Junction Box) C2280B-49, circuit CLF21 (GY/VT), harness side.





Is the resistance less than 5 ohms?

Yes
GO to S5.

No
REPAIR circuit CLF21 (GY/VT) for an open. TEST the system for normal operation.

S4 BYPASS THE SJB (Smart Junction Box)

- Ignition OFF.

- Disconnect: SJB (Smart Junction Box) C2280E.

- Connect a fused jumper wire between the SJB (Smart Junction Box) C2280E-1, circuit CDC34 (WH/OG), harness side and the SJB (Smart Junction Box) C2280E-3, circuit CLF12 (BN/YE), harness side.





- Ignition ON.

Do the fog lamps illuminate?

Yes
REMOVE the jumper wire. GO to S5.

No
REMOVE the jumper wire. REPAIR circuit CLF12 (BN/YE) for an open. TEST the system for normal operation.

S5 CHECK FOR CORRECT SJB (Smart Junction Box) OPERATION

- 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.