Cruze

DTC P0685

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 under bonnet 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.

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.

DTC P06865 00 is a Type B DTCs.

DTC P06865 00 is a Type B DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

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 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.

1. Ignition OFF, remove the KR75 Powertrain Relay, from the under bonnet 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 terminal 62 (X2). If the circuit tests normal, replace the K20 Engine Control Module.

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 terminal 62 (X2). If the circuit tests normal, replace the K20 Engine Control Module.

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 terminal 62 (X2). If the circuit tests normal, replace the K20 Engine Control Module.

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 terminal 22 (X2), T8 Ignition Coil pin B, B52A Heated Oxygen Sensor 1 pin 4, and B52B Heated Oxygen Sensor 2 pin 4. If the circuits tests normal, replace the K20 Engine Control Module.

7. Ignition OFF, disconnect K20 Engine Control Module, test for less than 5 Ω between KR75 Powertrain Relay Socket Terminal 87 and K20 Engine Control Module terminal 22 (X2).

⇒	If the resistance measures greater than 5 Ω, repair the open/high resistance between K20 Engine Control Module terminal 22 (X2) and KR75 Powertrain Relay Socket Terminal 87.

8. Ignition OFF, connect K20 Engine Control Module connector (X2), insert KR75 Powertrain Relay. Turn the ignition ON. Test for greater than 11 V between K20 Engine Control Module terminal 22 (X2) and ground.

Relay 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.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.