Diagnostic Instructions

DTC Descriptors

DTC P0685: Engine Controls Ignition Relay Control Circuit

DTC P0690: Engine Controls Ignition Relay Feedback Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
Battery Supply Voltage - Coil	P0685	P0685	P0685	--	--
Battery Supply Voltage - Armature	P0689	P0689	P0689	--	--
Relay Control Circuit	P0685	P0685	P0685	P0685	--
Relay Feedback Circuit	--	--	--	P0690	--

Typical Scan Tool Data

EC Ignition Relay Feedback Signal

Circuit	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 V¹
¹DTC 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 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 fuses in the underhood fuse block.

The ignition 1 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 ignition 1 voltage circuit to confirm that the powertrain relay contacts have closed.

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

Reference Information

Schematic Reference

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

J 43244 Relay Puller Pliers

Circuit/System Verification

1. Ignition ON, verify that the Feedback Circuit parameter indicates B+ voltage.
2. Ignition ON, command the powertrain relay ON and OFF. Listen or feel to verify that the powertrain relay turns ON and OFF with the commanded states.

Circuit/System Testing

1. Ignition OFF, disconnect the Powertrain Relay using the J 43244 Pliers .
2. Ignition ON, verify that a test lamp does not illuminate between the ignition circuit terminal 30 and ground.

⇒	If the test lamp illuminates, test the ignition circuit for a short to voltage.

3. Ignition OFF, verify that a test lamp illuminates between the B+ circuit 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.

4. Verify that a test lamp illuminates between the B+ circuit terminal 87 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.

5. Disconnect the X2 harness connector at the ECM.
6. Test for less than 2 ohms between ground and the ECM terminal 73 X2

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

7. Ignition ON, verify that a test lamp illuminates between connector terminal 19 X1 and ground.

⇒	If the test lamp does not illuminate, test the circuit for an open/high resistance and a short to ground. If the circuit tests normal and its fuse is open, replace the ECM.

8. Ignition OFF, connect the harness connector at the ECM.
9. Ignition ON, connect a jumper wire between the B+ circuit terminal 87 and the ignition circuit terminal 30. Verify that the EC Ignition Relay Feedback Signal parameter indicates B+ voltage.

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

10. Ignition OFF, allow the ECM to completely power down.
11. Verify that a test lamp does not illuminate between the 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.

12. Remove the test lamp.
13. Ignition ON, verify the scan tool EC 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.

14. Install a 3A fused jumper wire between the control circuit terminal 85 and the B+ circuit terminal 86. Verify the scan tool EC Relay Ckt. Short Volts Test Status Parameter is Fault.

⇒	If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

15. If all circuits test normal, replace the Powertrain Relay.

Component Testing

1. Measure for 70-110 ohms between terminals 85 and 86 of the relay.

⇒	If the resistance is not within the specified range, replace the relay.

2. Measure for infinite resistance between terminals 30 and 86 of the relay.

⇒	If continuity is detected, replace the relay.

3. Measure for infinite resistance between terminals 30 and 87 of the relay.

⇒	If continuity is detected, replace the relay.

4. Measure for infinite resistance between terminals 30 and 85 of the relay.

⇒	If continuity is detected, replace the relay.

5. Measure for infinite resistance between terminals 85 and 87 of the relay.

⇒	If continuity is detected, replace the relay.

6. Connect a 20A fused jumper wire from the battery positive cable at the battery, to relay terminal 85. Connect a jumper wire from the negative battery cable at the battery, to relay terminal 86. Measure for less than 2 ohms between terminals 30 and 87 of the relay, with a DMM.

⇒	If the resistance measures more than 2 ohms, replace the relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.