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 of the diagnostic category. |
DTC Descriptors
DTC P0685: Engine Controls Ignition Relay Control CircuitDTC 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 | -- | -- | -- | -- | -- |
Relay Control Circuit | P0685 | P0685 | P0685 | P0685 | -- |
Relay Feedback Circuit | -- | -- | -- | P0690 | -- |
Typical Scan Tool Data
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
| • | The battery voltage is between 9-18V. |
| • | The ignition is ON. |
| • | The powertrain relay has been commanded ON. |
P0690
| • | The battery voltage is between 9-16V. |
| • | The ignition is OFF. |
| • | The powertrain relay has been commanded OFF. |
Conditions for Setting the DTC
P0685
| • | The commanded state of the ODM does not match and the actual state of the control circuit. |
| • | The condition is present for more than 5 seconds. |
P0690
| • | The ECM detects more than 2V on the ignition 1 voltage circuit to the ECM. |
| • | 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 assumes that the vehicle battery has passed a load test and is completely charged. |
| • | When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect the component electrical terminals for corrosion and the mating electrical terminals for correct tension. |
Reference Information
Schematic Reference
Connector End View Reference
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
- Ignition ON, verify that the Feedback Circuit parameter indicates B+ voltage.
- 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
- Ignition OFF, disconnect the Powertrain Relay using the J 43244 Pliers .
- Ignition ON, verify that a test lamp does not illuminate between the ignition circuit terminal 30 and ground.
- Ignition OFF, verify that a test lamp illuminates between the B+ circuit terminal 86 and ground.
- Verify that a test lamp illuminates between the B+ circuit terminal 87 and ground.
- Disconnect the X2 harness connector at the K20 ECM.
- Test for less than 2Ω between ground and the K20 ECM terminal 73 X2
- Ignition ON, verify that a test lamp illuminates between connector terminal 19 X1 and ground.
- Ignition OFF, connect the harness connector at the K20 ECM.
- 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.
- Ignition OFF, allow the K20 ECM to completely power down.
- Verify that a test lamp does not illuminate between the B+ circuit terminal 86 and the control circuit terminal 85.
- Remove the test lamp.
- Ignition ON, verify the scan tool EC Relay Ckt. Short Volts Test Status Parameter is OK.
- 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 all circuits test normal, replace the Powertrain Relay.
| ⇒ | If the test lamp illuminates, test the ignition circuit for a short to voltage. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | 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 K20 ECM. |
| ⇒ | If the parameter does not indicate B+ voltage, test the ignition circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the K20 ECM. |
| ⇒ | If not the specified value, test the control circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM. |
| ⇒ | If not the specified value, test the control circuit for an open/high resistance. If the circuit tests normal, replace the K20 ECM. |
Component Testing
- Measure for 70-110Ω between terminals 85 and 86 of the relay.
- Measure for infinite resistance between terminals 30 and 86 of the relay.
- Measure for infinite resistance between terminals 30 and 87 of the relay.
- Measure for infinite resistance between terminals 30 and 85 of the relay.
- Measure for infinite resistance between terminals 85 and 87 of the relay.
- 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 2Ω between terminals 30 and 87 of the relay, with a DMM.
| ⇒ | If the resistance is not within the specified range, replace the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| ⇒ | If the resistance measures more than 2Ω, replace the relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
