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 P0685: Engine Controls Ignition Relay Control Circuit
DTC P0689: Engine Controls Ignition Relay Feedback Circuit Low Voltage
DTC P0690: Engine Controls Ignition Relay Feedback Circuit High Voltage

### Circuit/System Description

The engine controls ignition relay or main relay, is controlled by the engine control module (ECM). 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, and the switch side of the relay.

### Conditions for Running the DTC

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

• | The ignition voltage is between 11-18 volts.

• | The DTC runs continuously once the above conditions are met.

### Conditions for Setting the DTC

#### P0685

The ECM detects that the commanded state of the driver and the actual state of the control circuit do not match for greater than 2 seconds.

#### P0689

The ECM detects the engine controls ignition relay feedback circuit is less than 5 volts when the relay is commanded ON for 5 seconds.

#### P0690

• | The ECM detects the engine controls ignition relay feedback circuit is greater than 2 volts when the relay is commanded OFF.

• | The ECM detects the engine controls ignition relay feedback circuit is greater than 18 volts when the relay is commanded ON.

### Action Taken When the DTC Sets

DTCs P0685, P0689, and P0690 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P0685, P0689, and P0690 are Type B 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, command the EC ignition relay ON and OFF, with a scan tool, while observing the scan tool EC Ign. Relay Feedback Signal. The parameter should display less than 0.5 V when commanded OFF, and B+ when commanded ON.
2. Ignition ON, command the EC ignition relay ON and OFF, with a scan tool, while observing the following control circuit status parameters:

• | EC Ign. Relay Ckt Short Gnd Test Status

• | EC Ign. Relay Ckt Open Test Status

• | EC Ign. Relay Ckt Short Volts Test Status

• | Each parameter should display OK or Not Run.

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 EC ignition relay.
2. Ignition ON, verify a test lamp illuminates between both of the following relay ignition circuit terminals and ground.

• | Terminal 85

• | Terminal 30

⇒ | If the test lamp does not illuminate, repair the relay ignition 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 B+. The test lamp should not illuminate.

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

Note: The DMM will display 8.0-9.0 V on the control circuit when the ignition switch is transitioned from ON to OFF.

4. Ignition OFF for 1 minute, test for 0.0 V between the control circuit terminal 86 and B+.

⇒ | If greater than the specified value, test the control circuit for an short to voltage. If the circuit/connections test normal, replace the ECM.

5. Ignition ON, test for greater than 10.0 V between the control circuit terminal 86 and B+.

⇒ | If less than the specified value, test the control circuit for an open/high resistance. If the circuit/connections test normal, replace the ECM.

6. Connect a 15 A fused jumper wire between the relay switch ignition voltage circuit terminal 87 and B+. Observe the scan tool EC Ign. Relay Feedback Signal parameter. The reading should display B+.

⇒ | If less than the specified range, test the relay switch ignition voltage circuit for a short to ground or for an open/high resistance. If the circuit tests normal, replace the ECM.

7. If all circuits test normal, test or replace the EC ignition relay.

### Component Testing

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

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

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