GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2009 🢒 CTS 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P0685 or P0690

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

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

Open/High Resistance

Short to Voltage

Signal Performance

Relay Coil B+

P0685

P0685

--

--

Relay Coil Control

P0685

P0685

P0685

--

Relay Ignition Output Ignition 1 Voltage

--

--

P0690

--

Typical Scan Tool Data

EC Ignition Relay

Display Parameters

Normal Range

Short to Ground

Open/High Resistance

Short to Voltage

Operating Conditions: Ignition ON, engine OFF, powertrain relay commanded ON.

EC Ignition Powertrain Relay Circuit Status

OK/Incomplete

Short to GRD/Open

Short to GRD/Open

Short to B+

EC Ignition Powertrain Relay Command

ON

ON

ON

ON

EC Ignition Powertrain Relay Feedback Signal

12-12.9 V

0.0 V

0.0 V

12-12.9 V

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

    • The ignition is ON.
    • The battery voltage is between 9-16 volts.

P0690

    • This DTC will run with the ignition ON or OFF.
    • This DTC will run when the powertrain relay is commanded ON or OFF.
    • DTC  P0685 is not set.

Conditions for Setting the DTC

P0685

    • The commanded state of the ODM and the actual state of the control circuit do not match.
    • The condition is present for more than 5 seconds.

P0690

    • The ECM detects more than 16 volts on the ignition 1 voltage circuit to the ECM when the relay is commanded ON.
    • The ECM detects more than 2 volts on the ignition 1 voltage circuit to the ECM when the relay is commanded OFF.
    • The condition is present for more than 2 seconds.

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

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Special Tools

    • J 35616 GM-Approved Terminal Test Kit
    • J 43244 Relay Puller Pliers

Circuit/System Verification
  1. Ignition ON, engine OFF, command the powertrain relay ON and OFF, with a scan tool, while observing the following powertrain relay coil control circuit status parameters.
    2. • 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 or 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.

Circuit/System Testing

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

  1. Ignition OFF, disconnect the powertrain relay.
  2. Ignition ON, verify that a test lamp illuminates between the powertrain relay coil B+ terminal 85 and ground.
    3. ⇒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+ terminal 85 circuit and the control circuit terminal 86.
    4. ⇒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.
    6. ⇒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 terminal 85 and 86 for 60-250 ohms.
    7. ⇒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.
    9. ⇒If the circuit tests normal, replace the ECM.
  9. Verify that a test lamp does not illuminate between the relay ignition 1 terminal 87 voltage circuit and ground.
    10. ⇒If the test lamp illuminates, test the relay ignition 1 voltage circuit terminal 30 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.
    11. ⇒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 30 and the relay ignition 1 voltage circuit terminal 87.
  12. Ignition ON, engine OFF, monitor the EC Ignition Relay Feedback parameter with a scan tool. The parameter should display B+.
    13. ⇒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
    •  Engine Control Module Programming and Setup
    •  Engine Control Module Replacement
    •  Relay Replacement

Repair Verification
  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.
    6. ⇒If another DTC is present, refer to Diagnostic Trouble Code (DTC) List - Vehicle and perform the appropriate diagnostic procedure.