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.

### DTC Descriptor

DTC P068A 00: Engine Controls Ignition Relay De-Energized Too Early
DTC P068B 00: Engine Controls Ignition Relay De-Energized Too Late

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Relay Coil Ignition | P068A 00 | P068A 00 | -- | --
Relay Switch B+/Ignition | P068A 00 | P068A 00 | -- | --
Relay Coil Control | P068B 00 | -- | -- | --
Relay Controlled Output | -- | -- | P068B 00 | --

### Circuit/System Description

The powertrain relay is controlled by the engine control module (ECM) depending upon input from the ignition switch. Battery positive voltage is supplied to the relay coil and switch. When the ignition switch is turned to the ON position, the ECM will provide ground on the control circuit of the relay using a low side driver. This will allow voltage through the relay switch contacts to the components. The ECM monitors the voltage level on the control circuit of the relay.

### Conditions for Running the DTC

#### P068A

• | The ignition is ON or the engine is running.

• | The DTCs run continuously once the above condition is met.

#### P068B

• | The ignition is switched OFF.

• | The DTC runs continuously until the ECM powers down.

### Conditions for Setting the DTC

The ECM detects the powertrain relay control circuit is open, shorted to ground, or shorted to voltage.

### Action Taken When the DTC Sets

DTCs P068A or P068B are Type C DTCs.

### Conditions for Clearing the DTC

DTCs P068A or P068B are Type C DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Circuit/System Verification

Note: If you were sent here from Engine Cranks But Does Not Run proceed to Circuit/System Testing.

1. Ignition ON, observe the DTC information with a scan tool. DTCs P068A or P068B should not set.
2. Cycle the ignition from OFF to ON. You should hear and feel an audible click from the KR75 Powertrain Relay. Repeat as necessary in order to verify KR75 Powertrain Relay operation.
3. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Ignition OFF, disconnect the KR75 Powertrain Relay.
2. Ignition ON, verify that a test lamp illuminates between the relay coil ignition voltage circuit terminal 85 and ground.

⇒ | If the test lamp does not illuminate, repair the relay coil ignition voltage circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect a test lamp between the relay coil control circuit terminal 86 and the relay coil ignition voltage circuit terminal 85. The test lamp should not be illuminated.

⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Ignition ON. The test lamp should turn ON.

⇒ | 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 K20 Engine Control Module (ECM).

5. Connect a 20 A fused jumper wire between the relay switch B+ circuit terminal 30 and the relay switch ignition voltage circuit terminal 87.
6. Attempt to start the engine. The engine should start.

⇒ | If the engine does not start, test the ignition circuit between the KR75 Powertrain Relay and the K20 Engine Control Module (ECM) for a short to ground or for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

7. If all circuits test normal, test or replace the KR75 Powertrain Relay.

### Component Testing

1. Ignition OFF, disconnect the main ignition relay.
2. Test for 70-110 Ω between terminals 85 and 86.

⇒ | If not within the specified range, replace the KR75 Powertrain 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 KR75 Powertrain Relay.

4. Install a 10 A fused jumper wire between relay terminal 85 and 12 V. Install a jumper wire between relay terminal 86 and ground. Test for less than 2 Ω between terminals 30 and 87.

⇒ | If greater than the specified range, replace the KR75 Powertrain Relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Ignition Relay Diagnosis

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