Normal Operation

WARNING: This page is about a different car, the 2007 Mercury Mariner and 2007 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

The smart junction box (SJB) receives fused battery power from the battery junction box (BJB) fuse 17 (50A) circuit 16 (RD/LG). The SJB then provides the ignition switch with fused battery power through fuse 4 (10A) circuit 1715 (RD). The ignition switch has 4 possible states:

OFF - No power on any circuit to the SJB.
RUN/ACC - Power on circuit 297 (BK/LG) to the SJB.
RUN/START - Power on circuit 306 (TN/LB) to the starter relay and power on circuit 1050 (LG/VT) to the SJB.
RUN - Power on circuits 1050 (LG/VT) and 297 (BK/LG) to the SJB.

Possible Causes

Fuse(s)
Circuit open
Ignition switch
SJB