Normal Operation
WARNING: This page is about a different car, the 2009 Mercury Sable, 2009 Ford Taurus X, and 2009 Ford Taurus. However, it is still accessible from the selected car via links, so may be relevant.
The Battery Junction Box (BJB) receives battery voltage along circuit SDC02 (RD) and distributes this voltage to various fuses. The ignition switch receives fused battery voltage from BJB fuse 33 (20A) along circuit SBB33 (RD). The ignition switch then sends that voltage out to various systems depending on ignition switch position. The ignition switch has 4 possible states:
- OFF - Power on circuit CDC30 (BU/GY) to the Smart Junction Box (SJB)
- ACC - Power on circuit CDC33 (VT/GN) to the SJB
- RUN - Power on circuit CDC34 (WH/OG) to the SJB and BJB
- START - Power on circuit CDC35 (BU/WH) to the PCM and the One-Touch Integrated Start (OTIS) diode in the BJB. From the OTIS diode, the voltage is sent to the SJB, the PCM and the starter relay in the BJB along circuit CE336 (GN/WH).
The SJB continually monitors the ignition switch position and will set DTCs when certain conditions exist.
- B2844 Ignition Fault - If the SJB receives an invalid ignition switch state or cannot detect the ignition switch state during normal operation, DTC B2844 is set.
- U2472 Unexpected Ignition State - If during the SJB on-demand self test, the SJB does not receive the ignition RUN signal or any ignition switch signal, DTC U2472 is set.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Ignition switch
- SJB