Normal Operation

WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.

In normal operation, voltage from the central junction box (CJB) is supplied to the ignition switch through circuit 1050 (LG/VT). When the ignition switch is placed in the START position, voltage is supplied through circuit 32 (RD/LB) to the CJB.

For automatic transmission equipped vehicles, voltage is supplied from the CJB to the digital transmission range (TR) sensor through circuit 325 (DB/OG). In PARK or NEUTRAL, voltage is supplied from the TR sensor through circuit 1093 (TN/RD) to the starter relay coil located in the CJB. The starter relay coil is supplied ground from the powertrain control module (PCM) through circuit 1785 (LG/VT).

For manual transmission equipped vehicles, voltage from the CJB is supplied to a loop circuit in the 15525 transmission harness through circuit 325 (DB/OG). Voltage is supplied from the loop circuit through circuit 1093 (TN/RD) to the starter relay coil located in the CJB. The starter relay coil is supplied ground from the PCM through circuit 1785 (LG/VT). The PCM will not provide ground to the starter relay coil unless the clutch is depressed, grounding the clutch pedal position bottom of travel input to the PCM, on circuit 1903 (WH/BK).

When the starter relay is energized, voltage supplied to the relay switch is sent to the starter motor solenoid through circuit 113 (YE/LB). Battery voltage is supplied to the starter motor through circuit 2037 (RD) at all times.

Possible Causes

Battery
An open in circuit 1050 (LG/VT), 325 (DB/OG), 1093 (TN/RD), 1785 (LG/VT), 570 (BK/WH), 1903 (WH/BK) or the transmission wiring harness
PCM
Digital TR switch
Ignition switch
Starter motor relay
Clutch pedal position (CPP) switch