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
--- | --- | --- | --- | ---
B+ | 1 | 1 | -- | --
CRNK Fuse | -- | 1 | -- | --
ECM/TRANS Fuse | -- | 1 | -- | --
Park/Neutral Signal (MN5) | 2 | 1 | 1 | --
CRNK Relay Control | 1 | 1 | 3 | --
Starter Solenoid Control | 1 | 1 | 3 | --
Ground | -- | 1 | -- | --

1. No crank
2. Cranks in any gear
3. Cranks all the time

### Typical Scan Tool Data

#### Ignition 1 Signal - ECM

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Ignition ON, engine OFF. Parameter Normal Value: 12.6 Volts
ECM/TRANS Ignition | 0.0 Volts | 0.0 Volts | 12.6 Volts

#### PNP Switch - ECM

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Operating Conditions: Transmission in Park Parameter Normal Value: Park/Neutral
Park/Neutral Signal | Park/Neutral | In Gear | In Gear

### Circuit/System Description

The engine control module (ECM) controls engine cranking based on a power mode input and the status of the clutch pedal position (CPP) sensor (Getrag M86 / Saab MU3), or the park/neutral position (PNP) switch (MN5 4T45-E). With the transmission in park or neutral, voltage at the ECM PNP switch signal circuit is low, or the CPP signal circuit indicates that the clutch pedal is pressed. This indicates to the ECM that conditions are acceptable for cranking. The ECM provides voltage to the starter relay coil control circuit. The relay provides voltage to the starter terminal A X1 and engages the starter solenoid.

### 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

### Circuit/System Verification

#### Automatic Transmission (MN5)

1. Ignition ON, transmission in park, observe the scan tool ECM PNP Switch parameter. The reading should be Park/Neutral.

⇒ | If not the specified value, refer to PNP Switch Circuit Malfunction.

2. Command the Starter Relay ON with a scan tool (L61/LNF), or turn the ignition switch to the START position (LE5). The starter solenoid should engage and the engine should crank.

⇒ | If the solenoid engages but the engine does not crank, refer to Starter Solenoid Clicks, Engine Does Not Crank.

⇒ | If the solenoid does not engage, refer to CRNK Relay Circuit Malfunction.

#### Manual Transmission (M86/MU3)

1. Ignition ON, observe the scan tool ECM CPP Sensor and the CPP Learn Status parameters. The scan tool CPP Sensor parameter should change when the clutch pedal is pressed and released, and the CPP Learn Status should be Complete.

⇒ | If not the specified values, refer to the appropriate procedure listed below:

• | Clutch Pedal Position Sensor Learn for the Getrag (M86) transmission

• | Clutch Pedal Position Sensor Learn for the Saab (MU3) transmission

2. Command the Starter Relay ON with a scan tool (L61/LNF), or turn the ignition switch to the START position (LE5). The starter solenoid should engage and the engine should crank.

⇒ | If the solenoid engages but the engine does not crank, refer to Starter Solenoid Clicks, Engine Does Not Crank.

⇒ | If the solenoid does not engage, refer to CRNK Relay Circuit Malfunction.

### Circuit/System Testing

#### PNP Switch Circuit Malfunction (MN5)

1. Inspect the PNP switch for proper adjustment. Refer to Park/Neutral Position Switch Adjustment.
2. Ignition OFF, disconnect the harness connector at the PNP switch.
3. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the ground circuit terminal 1 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

4. Verify that the scan tool ECM PNP Switch parameter is In Gear.

⇒ | If not the specified value, test the signal circuit terminal 12 for a short to voltage. If the circuit tests normal, replace the ECM.

5. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the ground circuit terminal 1. Verify that the scan tool ECM PNP Switch parameter is Park/Neutral.

⇒ | If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

6. If all circuits test normal, test or replace the PNP switch.

#### CRNK Relay Circuit Malfunction

1. Ignition ON, observe the scan tool ECM Ignition 1 parameter. The reading should be B+ voltage.

⇒ | If not the specified value, test the ECM/TRANS ignition circuit terminal 54 X2 (LNF) or terminal 19 X1 (L61/LE5) for a short to ground or an open/high resistance.

2. Ignition OFF, disconnect the CRNK relay. Refer to Relay Replacement.
3. Ignition OFF and scan tool disconnected, open and close the driver door, and wait 1 minute. Test for less than 5 ohms between the ground circuit terminal 85 and ground.

⇒ | If greater than the specified range, test the ground circuit for an open/high resistance.

4. Verify that a test lamp illuminates between the 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.

5. Connect a test lamp between the ground circuit terminal 85 and the control circuit terminal 86.
6. Ignition ON, transmission in Park (MN5) or clutch pedal pressed (M86/MU3). Command the starter relay ON and OFF with a scan tool (L61/LNF), or turn the ignition switch between the start and run positions (LE5). 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 voltage. If the circuit tests normal, replace the ECM.

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

7. Ignition OFF, connect the CRNK relay. Disconnect the X1 harness connector at the starter solenoid.
8. Ignition ON, transmission in park (MN5) or clutch pedal pressed (M86/MU3). Command the starter relay ON with a scan tool (L61/LNF), or turn the ignition switch to the START position (LE5). Verify that a test lamp illuminates between the starter terminal A X1 and ground.

⇒ | If the test lamp does not illuminate, test the starter control circuit for an open/high resistance. If the circuit tests normal, test or replace the CRNK relay.

9. If all circuits test normal, test or replace the starter.

### Component Testing

#### PNP Switch (MN5 4T45-E)

1. Ignition OFF, disconnect the harness connector at the PNP switch.
2. With the PNP switch in the following positions, test for infinite resistance between the ground terminal 1 and the signal terminal 12.

• | R

• | OD

• | D

• | 2

• | 1

⇒ | If not the specified value, replace the PNP switch.

3. With the PNP switch in the following positions, test for less than 2 ohms between the ground terminal 1 and the signal terminal 12.

• | P

• | N

⇒ | If greater than the specified range, replace the PNP switch.

#### CRNK Relay

1. Ignition OFF, disconnect the CRNK relay.
2. Test for 60-180 ohms between terminals 85 and 86.

⇒ | If not within the specified range, replace the relay.

3. Test for infinite resistance between the following terminals:

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If not the specified value, replace the relay.

4. Install a 20 amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 ohms between terminals 30 and 87.

⇒ | If greater than specified range, replace the relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Clutch Pedal Position Sensor Learn for the Getrag (M86) manual transmission.

• | Clutch Pedal Position Sensor Learn for the Saab (MU3) manual transmission.

• | Park/Neutral Position Switch Adjustment for the 4T45-E (MN5) automatic transmission.

• | Park/Neutral Position Switch Replacement for the 4T45-E (MN5) automatic transmission.

• | Relay Replacement

• | Starter Motor Replacement

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