Diagnostic Instructions

DTC Descriptor

DTC P0685: Engine Controls Ignition Relay Control Circuit

DTC P0686: Engine Controls Ignition Relay Control Circuit Low Voltage

DTC P0687: Engine Controls Ignition Relay Control Circuit High Voltage

DTC P0689: Engine Controls Ignition Relay Feedback Circuit Low Voltage

DTC P0690: Engine Controls Ignition Relay Feedback Circuit High Voltage

Diagnostic Fault Information

Important: A condition with the powertrain (PT) relay will set multiple DTCs. The DTCs listed in the table will only set if a condition exists with the PT relay.

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
B+ Supply Voltage - Coil	P0685	P0685	P0685	--	--
B+ Supply Voltage - Switch	--	P0689	P0689	P0690	--
Relay Control Circuit	P0686	P0685	P0685	P0687	P0685
Ignition 1 Voltage Circuit	--	P0689	P0689	P0690	--

Circuit/System Description

The Powertrain (PT) 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 switch 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.

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.

Conditions for Running the DTC

P0685, P0686, and P0687

P0689 and P0690

Conditions for Setting the DTC

P0685, P0686, and P0687

The commanded state of the output driver module (ODM) and the actual state of the control circuit do not match. The condition exists for a cumulative of 50 seconds.

P0689 and P0690

The ECM detects that PT relay feedback voltage is less than 6 volts, when the PT relay is commanded ON. The condition exists for a cumulative of 50 seconds.

Action Taken When the DTC Sets

DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.

Conditions for Clearing the MIL/DTC

DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.

Diagnostic Aids

The following table illustrates the ECM connector locations:

ECM Connector Location
X2	X1
Front of Vehicle

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 43244 Relay Puller Pliers

Circuit/System Verification

1. Ignition ON, clear the DTCs with a scan tool.
2. Turn OFF the ignition for 30 seconds.
3. Ignition ON, observe the scan tool DTC information. DTCs P0685, P0686, P0687, P0689, or P0690 should not set.
4. 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 are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing

1. Ignition OFF, disconnect the PT relay.
2. Ignition ON, load test for B+ between both of the PT relay circuit terminals C5, C6, and ground.

⇒	If less than the specified range, repair the appropriate circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect a test lamp between the control circuit terminal A6 of the PT relay and B+. Verify the test lamp does not illuminate.

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

4. Ignition ON. Verify the test lamp illuminates when the ignition switch is cycled ON.

⇒	If the test lamp remains OFF all the time, test for a short to voltage or an open/high resistance on the control circuit. If circuit/connections test normal, replace the ECM.

Important: The ignition 1 voltage circuit is between the PT relay and the ECM. The ignition 1 voltage is a feedback circuit.

5. Connect a 15A fused jumper wire between the B+ supply voltage circuit terminal C6, and the ignition 1 voltage circuit terminal A5, of the PT relay.
6. Attempt to start the engine. The engine should start.

⇒	If the engine does not start, test the ignition 1 voltage circuit between the PT relay and the ECM for a short to ground or for an open/high resistance. If the circuit/connections test normal, replace the ECM.

7. If all circuits/connections test normal, test or replace the PT relay.

Component Testing

1. Test for 70-110 ohms of resistance between terminals 85 and 86 of the PT relay.

⇒	If not within the specified range, replace the PT relay.

2. Test for infinite resistance between the following terminals of the PT relay:

•

30 and 86

•

30 and 87

•

30 and 85

•

85 and 87

⇒	If continuity is detected, replace the PT relay.

3. Connect a 15A fused jumper wire from the positive terminal of the battery to relay terminal 85. Connect a jumper wire from the negative terminal of the battery to relay terminal 86. Test for less than 2 ohms between terminals 30 and 87 of the relay.

⇒	If greater than the specified range, replace the PT relay.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.