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 situations.
01. Most Common Causes
- Faulty ECM/PCM power relay
- Short to voltage in the relay sense circuit
- Corroded or damaged wiring/connectors
- Failed ECM/PCM
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine may not start or stalls
- Intermittent electrical issues
- Reduced engine performance
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and freeze frame data.
Step 2: Visually inspect the ECM/PCM power relay and related wiring for damage or corrosion.
Step 3: Test the relay sense circuit voltage with a multimeter; compare to manufacturer specs.
Step 4: Check for shorts to voltage in the circuit using a wiring diagram.
Step 5: If all else is normal, test the ECM/PCM for internal faults.
04. Commonly Affected Makes
05. 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 unsafe driving conditions.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for relay replacement and basic wiring repair, but can be higher if the ECM/PCM needs replacement.