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 Descriptors

DTC P0685: Engine Controls Ignition Relay Control Circuit
DTC P0686: Engine Controls Ignition Relay Control Circuit Low Voltage
DTC P0687: Engine Controls Ignition Relay Control Circuit High Voltage
DTC P0689: Engine Controls Ignition Relay Feedback Circuit Low Voltage
DTC P0690: Engine Controls Ignition Relay Feedback Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance
--- | --- | --- | --- | --- | ---
B+ Supply Voltage - Coil | P0685 | P0685 | P0685 | -- | --
B+ Supply Voltage - Switch | -- | P0689 | P0689 | P0690 | --
Relay Control Circuit | P0686 | P0685 | P0685 | P0687 | P0685
Ignition Voltage Circuit | -- | P0689 | P0689 | P0690 | --

### Circuit/System Description

The engine controls (EC) ignition relay, or powertrain relay is a normally open relay. The relay switch is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the switch contact at all times. The engine control module (ECM) supplies the ground path to the relay coil control circuit via an internal integrated circuit called an output driver. When the ECM commands the relay ON, ignition voltage is supplied to the following fuses in the underhood fuse block:

• | ETC/ECM Fuse

• | EMISO 1 Fuse

• | EMISO 2 Fuse

• | EVEN COILS/INJ Fuse

• | ODD COILS/INJ Fuse

The ignition voltage that is supplied to the ECM through the ETC/ECM fuse, provides power to the internal ECM circuits associated with the throttle actuator control (TAC) operation.

### Conditions for Running the DTC

#### P0685, P0686, and P0687

• | The ignition voltage is between 10-18 volts.

• | The engine speed is greater than 80 RPM.

• | The powertrain relay has been commanded ON and OFF.

• | The DTCs run continuously when the above conditions are met.

#### P0689 and P0690

• | The ignition voltage is between 10-18 volts.

• | The ignition is ON.

• | The DTCs runs continuously when the above conditions are met.

### Conditions for Setting the DTC

#### P0685, P0686, and P0687

The commanded state of the ODM and the actual state of the control circuit do not match.

#### P0689 and P0690

The ECM detects that powertrain relay feedback voltage is less than 6 volts for greater than 500 mS.

### Action Taken When the DTC Sets

DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.

### Conditions for Clearing the MIL/DTC

DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.

### Diagnostic Aids

• | This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test.

• | An open in the relay control circuit will cause no communication with the ECM when the ignition switch is cycled OFF and ON after the initial failure. The malfunction indicator lamp (MIL) will flash rapidly and other relays can be heard turning ON and OFF with the ignition ON.

• | When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the correct orientation in the fuse block. Test the mating electrical terminals for tightness.

• | Use the J 35616 for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness connector terminals.

### 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

#### Special Tools

J 35616 Connector Test Adapter Kit

### Circuit/System Verification

1. Ignition ON, you should be able to communicate with the ECM using a scan tool.
2. Ignition ON, view the DTC information with a scan tool. DTCs P0685, P0686, P0687, P0689, or P0690 should not be set.
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 powertrain relay.
2. Ignition ON, load test for B+ between the ignition supply circuit terminal 85 and ground.

⇒ | If less than the specified range, test the ignition supply circuit for an open/high resistance.

3. Ignition ON, load test for B+ between the ignition supply circuit terminal 30 and ground.

⇒ | If less than the specified range, test the ignition supply circuit for an open/high resistance.

4. Ignition OFF, connect a test lamp between the control circuit terminal 86 of the powertrain relay and the B+ supply circuit terminal 85, coil side of the powertrain relay.
5. Turn ON the ignition. The test lamp should turn ON when the ignition switch is cycled ON and OFF when the ignition switch is cycled OFF.

⇒ | If the test lamp remains ON all the time, test for a short to ground on the control circuit. If the circuit/connections test normal, replace the ECM.

⇒ | If the test lamp remains OFF all the time, test for a short to voltage or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM.

Note: The ignition voltage circuit is between the powertrain relay and the ECM. The ignition voltage is a feedback circuit.

6. Connect a 15 A fused jumper wire between the B+ supply circuit terminal 30 and the ignition voltage circuit terminal 87 of the powertrain relay.
7. Attempt to start the engine. The engine should start.

⇒ | If the engine does not start, test the ignition voltage circuit between the powertrain relay and the ECM for a short to ground or for an open/high resistance. If the circuit/connections test normal, replace the ECM.

8. Ignition ON, test for less than 1 V between the ignition voltage circuit terminal 87 of the powertrain relay and ground.

⇒ | If greater than the specified value, repair the short to voltage in the ignition voltage circuit.

9. If all circuits/connections test normal, test or replace the powertrain relay.

### Component Testing

1. Test for 198-238 Ω between terminals 85 and 86 of the powertrain relay.

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

2. Measure the resistance between the terminals of the powertrain relay listed below. The DMM should display O.L.

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If less than the specified value, replace the powertrain relay.

3. Connect a 15 A fused jumper wire from the positive terminal of the battery to relay terminal 85. Connect a jumper wire from the negative terminal of the battery to relay terminal 86. Test for less than 2 Ω between terminals 30 and 87 of the relay.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

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