Normal Operation
WARNING: This page is about a different car, the 2007 Lincoln MKX and 2007 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.
The smart junction box (SJB) sends a voltage 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 on a separate output, circuit CLF12 (BN/YE) to the headlamp switch for the fog lamps on indicator.
- DTC B2254 (Front Fog Lamp Switch Failure) - is an on-demand DTC that sets when the SJB detects a short to ground on the fog lamp on input circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp switch
- SJB