Pinpoint Test C: The Engine Cranks Slowly

Starting System

Pinpoint Tests

Pinpoint Test C: The Engine Cranks Slowly

Refer to Wiring Diagram Set 20, Starting System for schematic and connector information. Diagrams By Number

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 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
- Ground circuit
- Starter motor


PINPOINT TEST C: THE ENGINE CRANKS SLOWLY

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C1 CHECK THE BATTERY


- Check the battery condition and charge. Refer to Battery, Mounting and Cables Testing and Inspection.
- Is the battery OK?

Yes
GO to C2.

No
CHARGE or INSTALL a new battery as required. TEST the system for normal operation.

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C2 CHECK THE VOLTAGE TO THE STARTER


- Ignition OFF.
- Measure the voltage between starter motor solenoid C197A-1, circuit 2037 (RD) and ground.




- Is the voltage 10 volts or greater?

Yes
GO to C3.

No
REPAIR circuit 2037 (RD). CLEAN and TIGHTEN the connections at the battery terminals. TEST the system for normal operation.

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C3 CHECK MOTOR GROUND CIRCUIT


- Carry out the Starter Motor - Ground Circuit test. Refer to the component tests. Component Tests and General Diagnostics
- Is the ground OK?

Yes
INSTALL a new starter motor. TEST the system for normal operation.

No
REPAIR the ground circuit as necessary. TEST the system for normal operation.

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