Normal Operation

WARNING: This page is about a different car, the 2009 Ford Mustang. However, it is still accessible from the selected car via links, so may be relevant.

When the headlamp switch is placed in the HEADLAMPS ON position, the smart junction box (SJB) monitors the multifunction switch by sending a voltage reference signal through circuit 1394 (WH/RD). When the multifunction switch is placed in the HIGH BEAM position, the signal is routed to an internal ground within the SJB through circuit 1396 (VT/WH). The SJB then supplies ground for the high beam relay coil through circuit 1708 (LG/BK). The high beam relay is supplied voltage at all times from the bussed electrical center (BEC). When the high beam relay is energized, voltage is routed to the high beams.

If the SJB is not configured for the correct headlamp type, the high beams may be inoperative.

DTC B2586 (Headlamp Mode Select Circuit Failure) - is an on-demand DTC that sets when the SJB detects a short to ground from the multifunction switch input (headlamp mode select) circuit.
DTC B2598 (Headlamp Relay Circuit Failure) - is a continuous and on-demand DTC that sets when the SJB detects an open or short to voltage from the high beam relay coil ground controlled circuit.

This pinpoint test is intended to diagnose the following:

Fuse
Wiring, terminals or connectors
SJB configuration
High beam relay
Multifunction switch
BEC
SJB