Diagnostic Instructions

DTC Descriptors

DTC P0685: Engine Controls Ignition Relay Control Circuit

DTC P0690: Engine Controls Relay Feedback Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
Battery Supply Voltage-Coil	P1516, P1682	P0685	P1516, P1682	--	--
Battery Supply Voltage-Armature	--	P1516, P1682	P1516, P1682	--	--
Ign 1 Relay Control Circuit	P0690	P0685	P1516, P1682	P0685, P1516, P1682, P2176	--
Ignition 1 Voltage Circuit	--	P1516, P1682	P1516, P1682	--	--

Typical Scan Tool Data

EC Ignition Relay Feedback Signal

Display Parameters	Normal Range	Short to Ground	Open	Short to Voltage
Operating Conditions: Ignition ON with the engine OFF
Battery Supply Voltage-Coil	--	0 V	0 V	--
Battery Supply Voltage-Armature	--	0 V	0 V	--
EC Ignition Relay Control	--	0 V	0 V	--
EC Ignition Relay Feedback	11.9-12.9 V	0 V	0 V	More than 2 V*
*DTC P0690 will set if the ECM detects voltage when the ignition is in the OFF position.

Circuit/System Description

The powertrain relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature 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 module (ODM). The ODM output control is configured to operate as a low side driver for the powertrain relay. 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 ECM, and to several additional circuits.

Conditions for Running the DTC

P0685

P0690

Conditions for Setting the DTC

P0685

P0690

Action Taken When the DTC Sets

DTCs P0685 and P0690 are Type B DTCs.

Conditions for Clearing the DTC

DTCs P0685 and P0690 are Type B 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.

Reference Information

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

Circuit/System Verification

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.

•	EC Ign. Relay Ckt. Short Gnd Test Status

•	EC Ign. Relay Ckt. Open Test Status

•	EC Ign. Relay Ckt. Short Volts Test Status

•	Each parameter should toggle between OK and Not Run.

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.

Circuit/System Testing

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

1. Ignition OFF, disconnect the Ign 1 relay.
2. Ignition ON, verify that a test lamp illuminates between the Ign 1 relay coil B+, 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 Ign 1 relay coil B+ circuit and the control circuit.

⇒	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 engine control ignition relay ON, with a scan tool. Verify with a scan tool that the EC Ign 1 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 Ign 1 relay for 65-110 ohms.

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

7. Ignition OFF, disconnect the ECM X1 connector.
8. Test the Ign 1 relay control circuit 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 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+ 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+ and the relay ignition 1 voltage circuit.
12. 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.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for ECM replacement, setup, and programming