Normal Operation
WARNING: This page is about a different car, the 2010 Mercury Milan, 2010 Lincoln MKZ, and 2010 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.
The Smart Junction Box (SJB) sends voltage signals to the headlamp switch through individual circuits (OFF, PARKING LAMPS and HEADLAMPS). At any given time, the headlamp switch routes one of the input circuits to ground.
When the SJB detects the headlamp switch in the HEADLAMPS ON position (or a fault with one of the headlamp switch input circuits for more than 5 seconds) and the multifunction switch in the LOW BEAM position, the SJB provides voltage to the headlamps.
For Milan and MKZ equipped with High Intensity Discharge (HID) headlamps, a relay is utilized to provide voltage for the low beam headlamps.
DTC FAULT TRIGGER CONDITIONS TABLE
| DTC Description | Fault Trigger Conditions |
|---|---|
|
An on-demand DTC that may set when the SJB detects the headlamps on input circuit is short to ground. |
|
An on-demand DTC that may set when the SJB detects multiple headlamp switch inputs active at the same time. |
|
An on-demand DTC that sets when the SJB detects the headlamp switch off input circuit open. |
|
An on-demand DTC that sets when the SJB detects the RH low beam output circuit shorted to voltage. |
|
An on-demand DTC that sets when the SJB detects the LH low beam output circuit shorted to voltage. |
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Headlamp relay
- Headlamp switch
- SJB