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

• | EMM DEV 1 Fuse

• | EMM DEV 2 Fuse

• | EVEN COIL/INJ Fuse

• | ODD COIL/INJ Fuse

The ignition voltage that is supplied to the ECM through the 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 once the above condition is met.

#### P0689 and P0690

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

• | The ignition is ON.

• | The DTCs runs continuously once the above condition is 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 for greater than a cumulative of 50 seconds.

#### P0689 and P0690

The ECM detects that powertrain relay feedback voltage is less than predicted range for greater than 1 second, when the powertrain relay is commanded ON or OFF. The condition exists for a cumulative of 50 seconds.

### 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 mating electrical terminals for tightness.

• | Use the J 35616 Connector Test Adapter Kit 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

• | Engine Control Module Connector End Views

• | Engine Controls 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

• | Scan Tool Data List

• | Scan Tool Data Definitions

• | Scan Tool Output Controls

### 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.

### Circuit/System Testing

1. Ignition OFF, disconnect the powertrain relay.

Important: The test lamp is used to load the circuit and may not illuminate.

2. Connect a test lamp between the B+ supply circuit to the coil side of the powertrain relay and the negative terminal of the battery.
3. Ignition ON, test for less than 0.1 volt between the B+ voltage circuit of the powertrain relay and the positive battery terminal.

⇒ | If greater than 0.1 volt, repair the B+ voltage circuit to the coil side of the powertrain relay for a short to ground or an open/high resistance.

Important: The test lamp is used to load the circuit and may not illuminate.

4. Connect a test lamp between the B+ voltage supply circuit to the switch side of the powertrain relay and the negative terminal of the battery.
5. Ignition ON, test for less than 0.1 volt between the B+ voltage circuit of the powertrain relay and the positive battery terminal.

⇒ | If greater than 0.1 volt, repair the B+ voltage circuit to the switch side of the powertrain relay for a short to ground or an open/high resistance.

6. With the ignition OFF, connect a test lamp between the control circuit of the powertrain relay and the B+ voltage supply circuit to the coil side of the powertrain relay.
7. 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.

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

8. Connect a 15A fused jumper wire between the B+ supply voltage circuit and the ignition voltage circuit of the powertrain relay.
9. 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.

10. Ignition ON, test for less than 1 volt on the ignition voltage circuit between the powertrain relay terminal in the UBEC and ground.

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

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

### Component Testing

1. Measure for 70-110 ohms of resistance between terminals 85 and 86 of the powertrain relay.

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

2. Measure for infinite resistance between the following terminals of the powertrain relay:

• | 30 and 86

• | 30 and 87

• | 30 and 85

• | 85 and 87

⇒ | If continuity is detected, replace the powertrain relay.

3. Connect a 15A 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. Measure for less than 2 ohms between terminals 30 and 87 of the relay.

⇒ | If the resistance measures more than 2 ohms, replace the powertrain relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

• | Control Module References for engine control module replacement, setup, and programming