Normal Operation
WARNING: This page is about a different car, the 2010 Mercury Mariner and 2010 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.
The Smart Junction Box (SJB) monitors the parking lamp request input from the headlamp switch. The SJB provides a ground for the parking lamp relay coil (integrated into the SJB ) when a request for the parking lamps is received. When the parking lamp relay is energized, voltage is routed to the rear and front parking lamps.
- DTC B1578 (Lamp Park Input Circuit Short to Ground) - an on-demand DTC that sets when the SJB detects a short to ground from the parking lamps on input circuit.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp switch
- SJB