For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Relay Control Circuit (terminal 85) |  | 1 | 1 | --
Relay Coil Voltage Supply Circuit (terminal 86) | -- | 1 | -- | --
Relay Control Output Circuit (terminal 87) | 1 | 1 | 2 | --
B+ Circuit (terminal 30) | 1 | 1 | -- | --

1. No crank
2. Cranks all the time

### Circuit/System Description

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.

### Reference Information

#### 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

• | Testing for Intermittent Conditions and Poor Connections

• | Circuit Testing

• | Wiring Repairs

• | Connector Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### Diagnostic Aids

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.

### Circuit/System Verification

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

### Circuit/System Testing

#### 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.

### Circuit/System Testing

#### 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.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Starter Motor Replacement

• | Relay Replacement

• | Transmission Range Switch Replacement

• | Clutch Pedal Engine Start Switch Replacement

• | Control Module References for ECM replacement, setup and programming