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 P0686: Engine Controls Ignition Relay Control Circuit Low VoltageDTC P0687: Engine Controls Ignition Relay Control Circuit High Voltage
DTC P0689: Engine Controls Ignition Relay Feedback Circuit Low Voltage
DTC P068B: Engine Controls Ignition Relay De-energized Too Late
Diagnostic Fault Information
Circuit | Short to Ground | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
Battery Supply Voltage - Coil | -- | -- | -- | -- | -- |
Battery Supply Voltage - Armature | P0689 | P0689 | P0689 | -- | -- |
Relay Control Circuit | -- | -- | -- | -- | -- |
Relay Feedback Circuit | P0689 | P0689 | P0689 | -- | -- |
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 | -- |
Battery Supply Voltage - Armature | -- | -- | 0 V | -- |
Powertrain Relay Control | -- | 0 V | 0 V | -- |
Ignition Voltage 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/engine controls (EC) ignition 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 relay also incorporates a fault detection circuit, which is continuously monitored by the ECM. When the ECM commands the 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
P0686 and P068B
| • | The ignition is ON. |
| • | The relay has been commanded ON. |
| • | These DTCs run continuously when the above conditions have been met. |
P0687 and P0689
| • | The ignition is OFF. |
| • | The powertrain relay has been commanded OFF. |
| • | These DTCs run continuously when the above conditions have been met. |
Conditions for Setting the DTC
| • | The commanded state of the ODM and the actual state of the control circuit do not match. |
| OR |
| • | The ECM detects that the feedback voltage is not within a predicted range when the relay is commanded ON and OFF. |
| • | Either condition is present for more than 2 seconds. |
Action Taken When the DTC Sets
DTCs P0686, P0687, P0689, and P068B are Type C DTCs.
Conditions for Clearing the DTC
DTCs P0686, P0687, P0689, and P068B are Type C DTCs.
Diagnostic Aids
| • | This test procedure assumes that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test. |
| • | 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
Circuit/System Verification
With the ignition ON, engine OFF, probe both test points of each of the fuses supplied with voltage by the powertrain relay.
| ⇒ | The test lamp should illuminate on at least one test point of each fuse. If the test lamp does not illuminate continue with Circuit/System Testing. |
Circuit/System Testing
- Ignition OFF, remove the powertrain relay, which is K12 relay, from the underhood fuse block.
- Ignition ON, measure for battery positive voltage, B+, between the relay coil voltage supply circuit and ground.
- Measure for voltage between the relay coil control circuit and ground.
- Ignition OFF, allow the 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.
- Turn the ignition ON. The test lamp should illuminate.
- Measure for B+ between the relay armature supply circuit, and ground.
- With the ignition ON, test for voltage on each test point of the ECM fuse, F21 fuse.
- Connect a 20A fused jumper wire between the B+ terminal and the ignition 1 voltage terminal of the powertrain relay at the underhood fuse block. With a test lamp, probe both test points of the ECM fuse.
| ⇒ | If the voltage measures less than B+, repair the open or high resistance in the circuit to the relay coil. All wire circuit resistance should measure less than 2 ohms. |
| ⇒ | If voltage is measured on the control circuit of the relay, test for a short to voltage. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
| ⇒ | If the test lamp is OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
| ⇒ | If the voltage measures less than B+, repair the open or high resistance in the circuit to the relay armature. All wire circuit resistance should measure less than 2 ohms. |
| ⇒ | If voltage is present, test the ignition 1 voltage circuit between the ECM and the powertrain relay for a short to voltage. |
| ⇒ | If both circuits test normal, replace the ECM. |
| ⇒ | If the test lamp illuminates at both test points of the F21 fuse, repair the ignition 1 voltage circuit between the powertrain relay and the ECM for an open or high resistance. If the circuit tests normal, replace the ECM. All wire circuit resistance should measure less than 2 ohms. |
| ⇒ | If the test lamp only illuminates at one test point of the F21 fuse, repair the short to ground in the ignition 1 voltage circuit between the fuse and the applicable component. Replace the fuse, as necessary. |
| ⇒ | If the test lamp does not illuminate on either test point of the F21 fuse, repair the open or high resistance between the powertrain relay and the ECM fuse. All wire circuit resistance should measure 2 ohms or less. |
Component Testing
- Measure for 70-110 ohms between terminals 85 and 86 of the powertrain relay.
- Measure for infinite resistance between following terminals of the powertrain relay:
- Connect a 20A 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. Measure for less than 2 ohms between terminals 30 and 87 of the relay.
| ⇒ | If the resistance is not within the specified range, replace the main relay. |
| • | Terminals 30 and 86 |
| • | Terminals 30 and 87 |
| • | Terminals 30 and 85 |
| • | Terminals 85 and 87 |
| ⇒ | If continuity is detected, replace the powertrain relay. |
| ⇒ | If the resistance measures more than 2 ohms, replace the powertrain relay. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for ECM replacement, setup, and programming |
