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 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 | P1516, P1682, P2101 | P0685 | P1682, P1516, P2101 | -- | -- |
Battery Supply Voltage - Armature | -- | P1516, P1682, P2101 | P1516, P1682, P2101 | -- | -- |
Powertrain Relay Control Circuit | P0690 | P0685 | P1516, P1682, P2101 | P0685, P1516, P1682, P2101, P2176 | -- |
IGN 1 Voltage Circuit | -- | P1516, P1682, P2101 | P1682, P1516, P2101 | -- | -- |
Typical Scan Tool Data
Circuit | Short to Ground | Open | Short to Voltage |
|---|---|---|---|
Operating Conditions: Ignition ON, with the engine OFF Parameter Normal Range: 11.9-12.9 V | |||
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 | 0 V | 0 V | More than 2 V¹ |
¹ DTC 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 9-18 volts. |
| • | The ignition is ON. |
| • | The powertrain relay has been commanded ON. |
P0690
| • | The battery voltage is between 9-16 volts. |
| • | 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 2 volts 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 A DTCs.
Conditions for Clearing the DTC
DTCs P0685 and P0690 are Type A 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
Special Tools Required
J 43244 Relay Puller Pliers
Circuit/System Verification
- With the ignition ON, engine OFF, command the engine control ignition relay ON and OFF several times using the scan tool output control function. You should either hear or feel the relay click with each command.
- With the ignition ON, engine OFF, probe both test points of each of the fuses supplied with voltage by the powertrain relay.
- Engine running, observe the DTC information with a scan tool. DTCs P0685 or P0690 should not set.
- 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.
| ⇒ | 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
- With the ignition OFF, remove the powertrain relay from the underhood fuse block.
- With the ignition ON, measure for battery positive voltage, B+, between the battery supply voltage coil circuit terminal R48 and ground.
- Measure for voltage between the powertrain relay control circuit and ground.
- Connect a test lamp between the battery supply voltage coil terminal R48 and the powertrain relay control circuit terminal R50. Use a scan tool to command the powertrain relay ON and OFF using the Engine Controls Ignition Relay selection. The test lamp should turn ON and OFF when toggling between the commanded states.
- Measure for B+ between the relay battery supply voltage switch circuit terminal R47, and ground.
- With the ignition ON, test for voltage on each test point of the V8 ECM fuse.
- Connect a 20A fused jumper wire between the B+ terminal R47 and the ignition 1 voltage terminal R49 of the powertrain relay at the underhood fuse block. With a test lamp, probe both test points of the V8 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 stays ON all the time, test for a short to ground on the powertrain relay control circuit or a faulty ECM. |
| ⇒ | If the test lamp stays OFF all the time, test for an open or high resistance on the powertrain relay control circuit or a faulty ECM. All wire circuit resistance should measure less than 2 ohms. |
| ⇒ | 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 V8 ECM, the powertrain relay, and the V8 ECM fuse for a short to voltage. |
| ⇒ | If both circuits test normal, replace the ECM. |
| ⇒ | If the test lamp illuminates at both test points of the V8 ECM fuse, repair the ignition 1 voltage circuit between the V8 ECM fuse and the ECM for an open, high resistance, or a faulty ECM. All wire circuit resistance should measure less than 2 ohms. |
| ⇒ | If the test lamp only illuminates at one test point of the V8 ECM 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 V8 ECM fuse, repair the open or high resistance between the powertrain relay and the V8 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 relay. |
| ⇒ | If the resistance is not within the specified range, replace the relay. |
| • | Measure for infinite resistance between terminals 30 and 86 of the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| • | Measure for infinite resistance between terminals 30 and 87 of the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| • | Measure for infinite resistance between terminals 30 and 85 of the relay. |
| ⇒ | If continuity is detected, replace the relay. |
| • | Measure for infinite resistance between terminals 85 and 87 of the relay. |
| ⇒ | If continuity is detected, replace 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 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 repair.
Control Module References for ECM replacement, setup, and programming.
