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 00: Engine Controls Ignition Relay Control Circuit
DTC P0689 00: Engine Controls Ignition Relay Feedback Circuit Low Voltage
DTC P0690 00: Engine Controls Ignition Relay Feedback Circuit High Voltage

### Circuit/System Description

The powertrain relay is an electrical switch that opens and closes under the control of the engine control module. The powertrain relay switch is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the relay switch contact at all times. The engine control module (ECM) supplies the ground path to the relay coil control circuit through an output driver module. The output driver module for the ignition main relay also incorporates a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the powertrain relay ON, switched battery voltage is supplied to fuses in the underhood fuse block. The switched battery voltage that is supplied to the ECM, provides power to the internal ECM circuits associated with the throttle actuator control (TAC) operation. The ECM also monitors the voltage level on the switched battery circuit to confirm that the powertrain relay contacts have closed.

### Conditions for Running the DTC

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

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

• | These DTC's run continuously once the above conditions are met.

### Conditions for Setting the DTC

#### P0685 00

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 s.

#### P0689 00

The ECM detects the engine controls powertrain relay feedback circuit is less than 5 V when the relay is commanded ON for 5 s.

#### P0690 00

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

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

### Action Taken When the DTC Sets

DTCs P06865 00, P0689 00, and P0690 00 are Type B DTCs.

### Conditions for Clearing the DTC

DTCs P06865 00, P0689 00, and P0690 00 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 diagnostic tester 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, you should be able to communicate with the ECM using a scan tool.
2. Ignition ON, view the DTC information with a scan tool. DTC P0685 00, P0689 00, P0690 00 should not 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, remove the KR75 Powertrain Relay, from the underhood fuse block.
2. Test for greater than 11 V between KR75 Powertrain Relay socket terminals 30, 85 and ground.

⇒ | If the voltage measures less than 11 V, repair the open or high resistance between B+ and KR75 Powertrain Relay socket terminal 30, 85.

3. Test for less than 0.3 V between KR75 Powertrain Relay Socket Terminal 86 and ground.

⇒ | If the voltage measures greater than 0.3 V, test the control circuit for a short to voltage between KR75 Powertrain Relay Socket Terminal 86 and K20 Engine Control Module (ECM) terminal 16 (X1). If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Verify that a test lamp does not illuminate between KR75 Powertrain Relay Socket Terminal 85 and KR75 Powertrain Relay Socket Terminal 86.

⇒ | If the test lamp illuminates, test the control circuit for a short to ground between KR75 Powertrain Relay Socket Terminal 86 and K20 Engine Control Module (ECM) terminal 16 (X1). If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. Turn the ignition ON. The test lamp should illuminate.

⇒ | If the test lamp is OFF, test the control circuit for an open/high resistance between KR75 Powertrain Relay Socket Terminal 86 and K20 Engine Control Module (ECM) terminal 16 (X1). If the circuit tests normal, replace the K20 Engine Control Module (ECM).

6. Test for less than 0.3 V between KR75 Powertrain Relay Socket Terminal 87 and ground.

Note: The T8 Ignition Coil , B52A Heated Oxygen Sensor (HO2S), and B52B Heated Oxygen Sensor (HO2S) are also powered by the KR75 Powertrain Relay.

⇒ | If the voltage measures greater than 0.3 V, test the ignition voltage circuits for a short to voltage between KR75 Powertrain Relay socket terminal 87 and K20 Engine Control Module (ECM) terminal 3 (X1), T8 Ignition Coil pin A (X1), B52A Heated Oxygen Sensor (HO2S) pin 1, and B52B Heated Oxygen Sensor (HO2S) pin 1. If the circuits tests normal, replace the K20 Engine Control Module (ECM).

7. Ignition OFF, disconnect K20 Engine Control Module (ECM), test for less than 5 Ω between KR75 Powertrain Relay Socket Terminal 87 and K20 Engine Control Module (ECM) terminal 3 (X1).

⇒ | If the resistance measures greater than 5 Ω, repair the open/high resistance between K20 Engine Control Module (ECM) terminal 3 (X1) and KR75 Powertrain Relay Socket Terminal 87.

8. Ignition OFF, connect K20 Engine Control Module (ECM) connector (X1), insert KR75 Powertrain Relay. Turn the ignition ON. Test for greater than 11 V between K20 Engine Control Module (ECM) terminal 3 (X1) and ground.

⇒ | If the voltage measures less than 11 V, replace the KR75 Powertrain Relay.

### Component Testing

#### Static Test

1. Measure for 70-110 Ω between terminals 85 and 86 of the KR75 Powertrain Relay.

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

2. Measure for infinite resistance between following terminals of the KR75 Powertrain Relay:

• | Terminals 30 and 86

• | Terminals 30 and 87

• | Terminals 30 and 85

• | Terminals 85 and 87

⇒ | If continuity is detected, replace the KR75 Powertrain Relay.

3. Connect a 20 A fused jumper wire from the positive terminal of the battery to KR75 Powertrain Relay terminal 85. Connect a jumper wire from the negative terminal of the battery to KR75 Powertrain Relay terminal 86. Measure for less than 5 Ω between KR75 Powertrain Relay terminal 30 and KR75 Powertrain Relay socket terminal 87.

⇒ | If the resistance measures more than 5 Ω, replace the KR75 Powertrain Relay.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Relay Replacement

• | Control Module Referencesfor Engine Control Module replacement, setup, and programming