ECM/PCM Power Relay Sense Circuit High
The P0690 code indicates that the Engine Control Module (ECM) or Powertrain Control Module (PCM) has detected a voltage higher than expected on the power relay sense circuit. This circuit monitors the voltage supplied to the ECM/PCM from the main relay. A high voltage reading can be caused by a faulty relay, wiring issues, or a failing ECM/PCM. This condition can lead to erratic engine behavior or no-start conditions.
1. Most Common Causes
- Faulty ECM/PCM power relay
- Short to voltage in the relay sense circuit
- Corroded or damaged relay socket or wiring
- Failing ECM/PCM
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine may not start or stalls
- Intermittent electrical issues
- Reduced engine performance
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm the code and check for additional codes.
Step 2: Inspect the ECM/PCM power relay and its socket for corrosion, damage, or loose connections.
Step 3: Test the relay sense circuit voltage with a multimeter; compare to manufacturer specifications.
Step 4: Check for shorts to voltage in the wiring between the relay and ECM/PCM.
Step 5: If all else is normal, test the ECM/PCM for internal faults.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it can cause the engine to stall or not start, leading to a safety hazard.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for parts and labor, depending on the cause and vehicle model.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.