Pinpoint Test A: The Engine Does Not Crank/the Relay Does/Does Not Click

Starting System

Pinpoint Tests

Pinpoint Test A: The Engine Does Not Crank/The Relay Does/Does Not Click

Normal Operation
Under normal operation, the Battery Junction Box (BJB) supplies constant power to the starter motor relay through fuse 13 (30A). When the key is placed in the START position, power is sent to the start diode through circuit CDC35 (BU/WH). Power continues through circuit CE336 (GN/WH) to the PCM and to the starter relay (TorqShift transmission) or the digital Transmission Range (TR) sensor (4R75 transmission). If the TR (Transmission Range) is in either the PARK or NEUTRAL position, power flows to the starter relay through circuit CET40 (GN/OG).
On vehicles equipped with a TorqShift transmission, the PCM will receive a signal from the transmission that the vehicle is in PARK or NEUTRAL through circuit VET32 (VT).
The PCM then provides ground on circuit CDC12 (YE) to the starter motor relay. The coil of the relay is energized and sends power to the starter motor on circuit CDC25 (BN/GN). The solenoid is grounded at the starter motor. Energizing the starter solenoid will engage the starter drive into the flexplate ring gear and closes the solenoid contacts allowing power directly from the battery through circuit SDC02 (RD) to the starter motor to start the engine.
The PCM will disengage the starter motor based on rpm threshold, a set time has been exceeded or the ignition key has been turned to the OFF position.

This pinpoint test is intended to diagnose the following:

- Battery
- Circuitry
- Fuse(s)
- Ignition switch
- PCM
- Start diode
- Starter motor
- Starter motor relay
- TR (Transmission Range) sensor