• | 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. |
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 Voltage Circuit | -- | P0689 | P0689 | P0690 | -- |
The engine controls (EC) ignition relay, or 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 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. When the ECM commands the powertrain relay ON, ignition voltage is supplied to several fuses in the underhood fuse block.
The fuse that provides power to terminal 3, 5, or 6 of ECM connector X2 feeds the internal ECM circuits associated with the throttle actuator control (TAC) operation.
• | The ignition voltage is between 10-18 volts. |
• | The engine speed is greater than 80 RPM. |
• | The powertrain relay has been commanded ON and OFF. |
• | The DTCs run continuously once the above condition is met. |
• | The ignition voltage is between 10-18 volts. |
• | The ignition is ON. |
• | The DTCs runs continuously once the above condition is met. |
The commanded state of the driver and the actual state of the control circuit do not match for greater than 4 seconds or for a cumulative of 30 seconds.
The ECM detects that powertrain relay feedback voltage is less than 6 volts for greater than 1 second, when the powertrain relay is commanded ON or OFF. The condition exists for 4 seconds, or for a cumulative of 30 seconds.
DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.
DTCs P0685, P0686, P0687, P0689, and P0690 are Type C DTCs.
• | This test procedure requires that the vehicle battery has passed a load test and is completely charged. Refer to Battery Inspection/Test. |
• | An open in the relay control circuit will cause no communication with the ECM when the ignition switch is cycled OFF and then ON after the initial failure. The malfunction indicator lamp (MIL) will flash rapidly and other relays can be heard turning on and off with the ignition ON. |
• | 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 tightness. |
• | Use the J 35616 Connector Test Adapter Kit for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness connector terminals. |
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
Note: The test lamp is used to load the circuit and may not illuminate.
⇒ | If greater than the specified value, repair the B+ voltage circuit to the coil side of the powertrain relay for a short to ground or an open/high resistance. |
Note: The test lamp is used to load the circuit and may not illuminate.
⇒ | If greater than the specified value, repair the B+ voltage circuit to the switch side of the powertrain relay for a short to ground or an open/high resistance. |
⇒ | If the test lamp remains ON all the time, test for a short to ground on the control circuit. If the circuit/connections test normal, replace the K20 ECM. |
⇒ | 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 K20 ECM. |
Note: The ignition voltage circuit is between the powertrain relay and the ECM. The ignition voltage is a feedback circuit.
⇒ | If the engine does not start, test the ignition voltage circuit between the powertrain relay and the ECM for a short to ground or for an open/high resistance. If the circuit/connections test normal, replace the K20 ECM. |
⇒ | If not within the specified range, replace the powertrain relay. |
• | 30 and 86 |
• | 30 and 87 |
• | 30 and 85 |
• | 85 and 87 |
⇒ | If continuity is detected, replace the powertrain relay. |
⇒ | If greater than the specified value, replace the powertrain relay. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for engine control module replacement, setup, and programming