Orlando

DTC P0686-P0689 or P068B

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.

P0686 00 and P0687 00

P0688 00 and P0689 00

P068B

The ECM detects the powertrain relay control circuit is open, shorted to ground, or shorted to voltage.

DTCs P0686 00, P0687 00, P0688 00, P0689 00 and P068B are Type C 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

Special Tools

EL 35616-E GM-Approved Terminal Test Kit

For equivalent regional tools, refer to Special Tools .

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 P0686 00, P0687 00, P0688 00, P0689 00 or P068B 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 underhood fuse block.
2. Test for greater than 11 V between KR75 Powertrain Relay socket terminals 2, 3 and ground.

⇒	If the voltage measures less than 11 V, repair the open or high resistance between B+ and KR75 Powertrain Relay socket terminal 2, 3.

3. Test for less than 0.3 V between KR75 Powertrain Relay socket terminal 1 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 1 and K20 Engine Control Module terminal 21 X1. 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 2 and KR75 Powertrain Relay socket terminal 1.

⇒	If the test lamp illuminates, test the control circuit for a short to ground between KR75 Powertrain Relay socket terminal 1 and K20 Engine Control Module terminal 21 X1. 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 1 and K20 Engine Control Module terminal 21 X1. 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 5 and ground.

⇒	If the voltage measures greater than 0.3 V, test the ignition voltage circuit for a short to voltage between KR75 Powertrain Relay socket terminal 5 and K20 Engine Control Module terminal 50 X1, 6 X2. If the circuit 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 5 and K20 Engine Control Module terminal 50 X1, 6 X2.

⇒	If the resistance measures greater than 5 Ω, repair the open or high resistance between K20 Engine Control Module terminal 50 X1, 6 X2 and KR75 Powertrain Relay socket terminal 5.

8. Ignition OFF, connect a 20 A fused jumper wire from the K20 Engine Control Module terminal 21 X1 to ground. Test for greater than 11 V between K20 Engine Control Module terminal 6 X2 and ground.

Static Test

1. Measure for 70-110 Ω between terminals 1 and 2 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 5 and 2

•	Terminals 5 and 3

•	Terminals 5 and 1

•	Terminals 1 and 3

⇒	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 socket terminal 2. Connect a jumper wire from the negative terminal of the battery to KR75 Powertrain Relay socket terminal 1. Measure for less than 5 Ω between KR75 Powertrain Relay socket terminal 3 and KR75 Powertrain Relay socket terminal 5.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.