Normal Operation
WARNING: This page is about a different car, the 2009 Mercury Milan, 2009 Lincoln MKZ, and 2009 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
The smart junction box (SJB) sends a reference signal to the headlamp switch through circuit CLF21 (GY/VT). When the fog lamp switch is engaged, the voltage signal is routed to ground.
Voltage is supplied to the switched side of the fog lamp relay from the battery junction box (BJB) fuse 24 (15A) through circuit SBB24 (VT/RD).
When the SJB detects the fog lamps on request, the SJB provides voltage to the fog lamp relay coil through circuit CLF29 (BN). The fog lamp relay coil ground is provided through circuit GD121 (BK/YE). When the fog lamp relay is energized, voltage is routed through circuit CLF12 (BN/YE) to the fog lamps.
- DTC B2030 (Front Fog Lamp Relay CKT Failure) - is a continuous DTC that sets when the SJB detects a short to ground on the fog lamp relay coil voltage supply circuit.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Fog lamp relay
- Headlamp switch
- SJB