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. The scan tool does not support the clutch pedal engine start switch, the clutch switch parameter displayed in scan tool is the cruise control cancel switch, which does not affect engine cranking.
2. Ignition ON, verify that no starter relay, automatic transmission, serial data, or related UEC, SCCM , ECM DTCs are set.

⇒	If other DTCs are set diagnosis those first.

1. Ignition ON, observe the scan tool SCCM Crank Request Signal parameter.
2. Place the ignition to the START position, the Crank Request Signal parameter should display Active.

⇒	If not the specified value, refer to Power Mode Description and Operation

3. Ignition ON, observe the scan tool ECM starter relay parameter.
4. Place the ignition to the START position, the parameter should display Active.

⇒	If not the specified value, refer to Diagnostic Trouble Code (DTC) List - Vehicle

Clutch Start Switch Circuit Malfunction

1. Disconnect the connector at the clutch pedal engine start switch.
2. Install a 3A fused jumper wire between terminal  1 X1 and terminal  2 X1.
3. Ensure the parking brake is applied and the transmission is in NEUTRAL.
4. Place the Ignition to the START position the starter should engage and the engine should begin cranking.

⇒	If the engine cranks with the fused jumper wire in place replace the clutch pedal engine start switch.

Automatic Transmission Range Switch Malfunction

1. Ignition ON, verify that no transmission range switch DTCs are set. (DTC  P0705 etc.)

⇒	If DTCs are set diagnose those first.

2. Ignition ON, with transmission in PARK verify the scan tool TCM PNP Switch parameter displays In PARK.

⇒	If not the specified value, Transmission Range Switch Adjustment

Starter Relay Circuit Malfunction

1. Ignition OFF, disconnect the starter relay.
2. Ignition ON, verify a test lamp illuminates between the relay coil B+ circuit terminal  86 and ground.

⇒	If the test lamp did not illuminate , test the circuit for a short to ground or an open/high resistance.

3. Ignition ON, verify a test lamp illuminates between the relay switch B+ circuit terminal  30 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

4. Ensure the parking brake is applied and the transmission is in NEUTRAL on manual transmissions or PARK on automatic transmissions.
5. Momentarily install a 40A fused jumper wire between the B+ circuit terminal  30 and the control output circuit terminal  87. The starter solenoid should engage and the engine should begin cranking.

⇒	If the solenoid does not engage, test the control output circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the starter motor.

6. Connect a test lamp between the relay coil control circuit terminal  85 and the relay coil B+ circuit terminal  86.
7. With the transmission range selector in park / neutral on automatic transmissions or the clutch pedal fully depressed on manual transmissions cycle the ignition between the OFF and CRANK position. The test lamp should turn ON and OFF when changing between the commanded states.

⇒	If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.