The OBD code P0686 for Cadillac indicates a fault with the ECM/PCM Power Relay Control Circuit Low.
This affects the Engine Control Module’s power relay circuit.
Symptoms include the Engine Light being ON.
Causes can be a weak battery, faulty ECM power relay, or wiring issues.
It is a moderate issue.
To fix, inspect and repair any damaged components or wiring connections related to the ECM power relay circuit.
| Repair Importance Level | 10.0 (Out of 10) |
| Estimated Repair Time | Approximately 1.0 hour |
| Repair Difficulty Level | 10.0 (Out of 10) |
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Symptoms of the Cadillac p0686 OBD Code
The vehicle may experience issues related to the engine control module power relay control circuit.
- Symptoms: Engine Light ON.
- Possible rough idle.
- Engine may stall or have difficulty starting.
- Loss of power while driving.
- Engine may run rough or hesitate during acceleration.
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Causes of the Cadillac p0686 OBD Code
P0686 in a Cadillac indicates a fault related to the ECM/PCM power relay control circuit.
- P0686 can be caused by a weak battery.
- Low voltage while cranking.
- A faulty Engine Control Module (ECM) power relay.
- An ECM power relay harness that is open or shorted.
- An ECM power relay circuit with poor electrical connection.
- A blown ECM fuse.
- Or a faulty ECM.
Fixing Cadillac Error Code p0686 Step By Step
Repair the wiring or connectors related to the ECM/PCM power relay control circuit for code P0686.
- To fix the Cadillac OBDII code P0686, start by reviewing the possible causes and visually examining the wiring harness and connectors associated with the engine control module (ECM).
- Check for any damaged components and inspect the connector pins for signs of being broken, bent, pushed out, or corroded.
- If no issues are found during the visual inspection, proceed to test the power supply to the ECM.
- Ensure that the ECM is receiving the correct voltage and ground signals.
- If the power supply checks out, consider reprogramming or replacing the ECM if necessary to resolve the P0686 fault code.
Cost Of Fixing Cadillac p0686 Fault Code
Diagnosing and repairing fault code P0686 on a Cadillac may involve testing and replacing components.
The cost to diagnose and fix the Cadillac OBD code P0686 depends on the estimated 1. 0hour repair time.
Labor rates usually range from $75 to $150 per hour, so the general cost could be between $75 and $150. The final cost may vary based on shop rates and the complexity of the repair.
Details of the Cadillac p0686 OBD Code
Code P0686 in a Cadillac indicates a fault with the ECM/PCM Power Relay Control Circuit High.
OBD code P0686 for Cadillac means that there is a fault in the ECM/PCM Power Relay Control Circuit.
This code is triggered when the ECM detects a voltage signal that is outside of the normal range for the power relay control circuit.
The power relay control circuit is responsible for providing power to the ECM/PCM.
When this circuit malfunctions, it can cause issues with the ECM’s ability to control various engine functions.
Mechanic’s Tech Notes
For Cadillac fault code P0686, refer to detailed diagnostic information for accurate troubleshooting and repair guidance.
To diagnose and fix OBDII code P0686 on a Cadillac, start by checking the Transmission Control Module (TCM) power and ground using a multimeter.
Verify TCM communication over the Controller Area Network (CAN) using a scan tool.
If the TCM does not respond, reprogramming or reflashing may be necessary.
Additionally, visually inspect the wiring harness and connectors for any damage, and ensure connector pins are not broken, bent, pushed out, or corroded.
This thorough inspection will help identify and address the root cause of the P0686 fault code.
FAQ
Common cause of OBD code P0686 in a Cadillac: Weak battery, faulty ECM power relay, or ECM power relay circuit issues. Check wiring and connectors for damage.
Diagnose P0686 in Cadillac by checking battery voltage, ECM power relay, harness, and connections. Inspect for damage, corrosion, or poor connections. Fix as needed.
Yes, OBD code P0686 can cause drivability issues in your Cadillac. It indicates a problem with the ECM power relay circuit.
Wrap Up
If your Cadillac is displaying OBD code p0686 and experiencing issues with the engine not starting or running poorly, it could be caused by a faulty ECM/PCM power relay control circuit.
This may lead to a lack of power supply to the ECM/PCM, resulting in starting or running problems.
To address Cadillac OBD code p0686, check the ECM/PCM power relay and its wiring for any damage or loose connections.
Test the relay operation and ensure proper power supply to the ECM/PCM.
Replace the relay if necessary and repair any wiring issues to restore proper functionality.
