Normal Operation

WARNING: This page is about a different car, the 2014 Lincoln MKX and 2014 Ford Edge. However, it is still accessible from the selected car via links, so may be relevant.

On vehicles equipped with a conventional ignition switch, fused battery voltage is sent to the ignition switch from Battery Junction Box (BJB) fuse 28 (15A). This voltage is then sent to the Body Control Module (BCM) along one of 3 circuits, depending on ignition switch position.

On vehicles equipped with a start/stop switch, fused battery voltage is sent to one set of contacts in the start/stop switch from Battery Junction Box (BJB) fuse 28 (15A). When the switch is pressed, this voltage is then sent to the Body Control Module (BCM), the Remote Function Actuator (RFA) module and the PCM. The other set of contacts in the start/stop switch connects the BCM to ground. When the switch is pressed, the BCM detects this ground signal and takes appropriate action.

DTC B108A:01 (Start Button: General Electrical Failure) - This DTC sets if the BCM does not receive any ignition signal during a BCM self-test or normal operation.
DTC B1142:29 (Ignition Status 1: Signal Invalid) - This DTC sets when the BCM does not receive a valid ignition signal during a BCM self-test.

This pinpoint test is intended to diagnose the following:

Wiring, terminals or connectors
Ignition switch (if equipped)
Start/stop switch (if equipped)
BCM