When the ignition switch is placed in the START position, a discrete signal is supplied to the steering column control module (SCCM) notifying it that the ignition is in the START position. The SCCM then sends a serial data message to engine control module (ECM) and the underhood electrical center (UEC), that CRANK has been requested. The UEC then supplies 12 volts to the coil side of the STARTER relay, when the ignition is in the start position. The ECM then supplies a ground to the control circuit of the starter relay. When this occurs, battery voltage is supplied through the switch of the starter relay through the closed PNP switch to the starter solenoid. On manual transmissions the clutch start switch interrupts the control circuit from the ECM to prevent the engine from cranking unless the clutch pedal is fully depressed.

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Starting System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Verify that battery is sufficiently charged and that the battery cables are clean and tight.

⇒	If the battery is not sufficiently charged, refer to Battery Charging

⇒	If battery cables are not torqued to within specified range, refer to Fastener Tightening Specifications .

2. Turn the ignition switch to the start position. The starter solenoid should click.

⇒	If starter solenoid does not click, refer to Starter Solenoid Does Not Click

3. Inspect the engine and belt drive system for mechanical binding, seized engine, or seized generator, etc.

⇒	If any of the conditions are observed, correct the condition.

4. Remove the drive belt, refer to Drive Belt Replacement
5. Turn the ignition switch to the START position. The engine should crank.

⇒	If the engine does not crank, refer to Engine Will Not Crank - Crankshaft Will Not Rotate

6. Using a DMM, measure between the positive battery cable and battery terminal at the solenoid as the ignition switch is turned to the START position. Voltage should be less than 0.5 volts.

⇒	If greater than the specified value, replace the positive battery cable.

7. Using a DMM, measure the negative battery cable to the starter motor case as the ignition switch is turned to the START position. Voltage should be less than 0.5 volts.

⇒	If greater than the specified value, replace the negative battery cable.

8. If all circuits test normal, test or replace the starter motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Starter Motor Replacement