The powertrain relay, which is PWR/TRN relay 33, 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 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 (ODM). The ODM for the powertrain relay also incorporates a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the powertrain relay ON, ignition 1 voltage is supplied to the fuses in the underhood fuse block.

The ignition 1 voltage that is supplied to the ECM through the ETC fuse, provides power to the internal ECM circuits associated with the throttle actuator control (TAC) operation. The ECM also monitors the voltage level on the ignition 1 voltage circuit to confirm that the powertrain relay contacts have closed.

P0685

P0690

P0685

P0690

DTCs P0685 and P0690 are Type B DTCs.

DTCs P0685 and P0690 are Type B DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Engine Control Module Description

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References

1. Engine running, command the powertrain relay ON and OFF, with a scan tool, while observing the following powertrain relay coil control circuit status parameters.

•	Powertrain relay coil control Ckt. Short Gnd Test Status

•	Powertrain relay coil control Ckt. Open Test Status

•	Powertrain relay coil control Ckt. Short Volts Test Status

•	Each parameter should toggle between OK and Not Run and Not Run and OK.

2. Ignition ON, engine OFF, with a test lamp, probe both test points of all the fuses that are powered by the powertrain relay. The test lamp should illuminate ON for at least one test point of each fuse.
3. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

Important: You must perform the Circuit/System Verification first.

1. Ignition OFF, disconnect the powertrain relay, which is PWR/TRN relay 33.
2. Ignition ON, verify that a test lamp illuminates between the powertrain relay coil B+ terminal 86 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the battery positive cable to the underhood fuse block.

3. Ignition OFF, verify that a test lamp does not illuminate between the powertrain relay coil B+ circuit terminal 86 and the control circuit terminal 85.

⇒	If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM.

4. Remove the test lamp.
5. Command the powertrain relay ON, with a scan tool. Verify with a scan tool that the powertrain relay Ckt. Short Volts Test Status parameter is OK.

⇒	If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

6. Test the coil side of the powertrain relay terminals 85 and 86 for 65-110 ohms.

⇒	If not within the specified value, replace the relay.

7. Ignition OFF, disconnect the ECM X1 connector.
8. Test the powertrain relay control circuit X1-40 for an open/high resistance.

⇒	If the circuit tests normal, replace the ECM.

9. Verify that a test lamp does not illuminate between the relay ignition 1 voltage circuit terminal 30 and ground.

⇒	If the test lamp illuminates, test the relay ignition 1 voltage circuit for a short to voltage. If the circuit tests normal, replace the ECM.

10. Verify that a test lamp illuminates between the relay switch B+ terminal 87 and ground.

⇒

If the test lamp does not illuminate, test the relay switch B+ circuit for a short to ground, or an open/high resistance. If the circuits test normal, and the fuse for the ignition 1 voltage circuit is open, test the ignition 1 voltage circuit to the ECM for a short to ground. If the circuit tests normal, replace the ECM.

11. Connect a 20 A fused jumper wire between the relay switch B+ terminal 87 and the relay ignition 1 voltage circuit terminal 30.
12. Connect the ECM. Ignition ON, engine OFF, monitor the EC Ignition Relay Feedback parameter with a scan tool. The parameter should display B+.

⇒	If the parameter does not display B+, test the ignition 1 voltage circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

13. If all circuits test normal, replace the relay.

1. Install any components that have been removed or replaced during diagnosis.
2. Perform any adjustment, programming, or setup procedures that are required when a component or module is removed or replaced.
3. Clear the DTCs.
4. Turn OFF the ignition for 60 seconds.
5. Ignition ON, command the powertrain relay ON and OFF with a scan tool, while observing the powertrain relay circuit status parameters. The circuit status parameters should change from OK to Not Run or Not Run to OK.

⇒	If another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle