P0686

P0686-POWER ENABLE CONTROL CIRCUIT LOW

For a complete wiring diagram, refer to the Wiring Information.

Theory of Operation

The Smart Power Relay supplies 12 Volts to the Mass Airflow Sensor, the Exhaust Gas Recirculation (EGR) Airflow Control Valve and the Variable Geometry Turbocharger. The Smart Power Relay Control circuit is a low side driver controlled by the Powertrain Control Module (PCM). The Smart Power Relay is powered up at key on, and remains powered until just after key off. The power supply to the Smart Power Relay is wired directly from the Totally Integrated Power Module (TIPM). The PCM will illuminate the Malfunction Indicator Lamp (MIL) and disable the regeneration mode immediately after this diagnostic runs and fails. During this time there will likely also be voltage supply faults for the Mass Airflow Sensor, the EGR Airflow Control Valve and the Variable Geometry Turbocharger. The PCM will turn off the MIL once the diagnostic runs and passes in four consecutive drive cycles.

- When Monitored:
Key on, Smart Power Relay commanded on.

- Set Condition:
The Smart Power Relay is commanded on by the PCM, and feedback voltage is reading high.





Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. Pre-Diagnostic Troubleshooting Procedure.

1. ACTIVE DTC
1. Ignition on, engine not running.
2. With the scan tool, read DTCs.

Is DTC active?

Yes

- Go To 2

No

- Perform the INTERMITTENT CONDITION diagnostic procedure. Intermittent Condition Test

2. POWERTRAIN CONTROL MODULE
1. Replace the Smart Power Relay.
2. Turn the ignition on.
3. With the scan tool, erase DTCs.
4. Turn the ignition off for 75 seconds.
5. Turn the ignition on.
6. With the scan tool, read DTCs.

Did the DTC reset?

Yes

- Replace Powertrain Control Module.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.

No

- Repair complete.
- Perform the POWERTRAIN VERIFICATION TEST - 6.7L. Powertrain Verification Test.