Pinpoint Test B : Engine Does Not Crank (With Push Button Start): Notes

Diagnostic Overview 

Diagnostics in this service information assume a certain skill level and knowledge of Ford-specific diagnostic practices. Refer to Diagnostic Methods for information about these practices.

Refer to Starting System - Wiring Diagrams .

Refer to Turn Signal/Stop/Hazard Lamps .

Normal Operation and Fault Conditions 

When the Start/stop switch is pressed in combination with the brake pedal, the RFA, BCM and PCM receive signals requesting to crank and start the engine. The PCM and RFA module receive notification from the TR sensor that the gear selector is in PARK or NEUTRAL. The PCM requires a voltage signal from the Run/start relay to operate. The PCM then supplies voltage and ground to the starter relay coil. The energized coil causes the starter relay contacts to close which allows voltage to be supplied from the BJB to the starter solenoid coil. The starter solenoid coil is grounded at the starter motor. Energizing the starter solenoid closes the solenoid contacts allowing voltage directly from the battery to the starter motor, engaging the starter drive into the ring gear causing the engine to crank. The PCM disengages the starter motor once an engine Revolutions Per Minute (RPM) threshold is reached, a set crank time is exceeded or the Start/stop switch is pressed indicating an engine shutdown request.

Fault Trigger Conditions 

Possible Sources 

• Battery
• Battery cables
• Fuses
• High current BJB connections
• Start/stop switch
• PCM
• Starter motor
• Starter motor bolts
• Wiring, terminals or connectors

Visual Inspection and Diagnostic Pre-checks 

• Inspect the Run/start relay.
• Inspect the Starter relay.
• Verify the BJB fuse 19 (30A).
• Verify the BCM fuse 18 (10A).
• Verify the BCM fuse 26 (5A).
• Inspect the IA Key.