The P0690 trouble code is a diagnostic trouble code (DTC) that indicates a problem with the ECM/PCM power relay sense circuit. This code is triggered when the powertrain control module (PCM) detects an abnormal voltage level in the relay circuit, which is responsible for supplying power to the PCM and its control circuits. Understanding this code is crucial for vehicle owners and DIY mechanics, as it can lead to various performance issues and even prevent the vehicle from starting.
| P0690 Code Meaning | P0690 Code Common Causes |
|---|---|
| ECM/PCM Power Relay Circuit High Voltage Detected | Faulty power relay |
| High voltage in the power relay sense circuit | Blown fuse or fusible link |
| Potential malfunction in the PCM | Open or shorted wiring in the circuit |
| Issues with battery connections | Corroded or damaged battery cables |
| Electrical system faults affecting voltage supply | Faulty ground connections for the PCM |
Symptoms of P0690 Code
When the P0690 code is triggered, several symptoms may manifest, indicating underlying issues. Recognizing these symptoms early can help in diagnosing and repairing the problem effectively.
- Check Engine Light: The most common symptom is the illumination of the check engine light on your dashboard.
- Starting Issues: The vehicle may experience delayed starts or may not start at all due to insufficient power reaching the PCM.
- Electrical Accessories Malfunction: Electrical components such as lights, radio, or other accessories may function erratically or not at all.
- Drivability Problems: The vehicle may exhibit poor performance, including stalling, rough idling, or hesitation during acceleration.
Technical Explanation of P0690 Code
The P0690 code signifies that the PCM has detected a high voltage condition in the power relay sense circuit. This circuit is vital for monitoring and controlling the voltage supplied to various systems within the vehicle’s powertrain. The PCM uses this information to ensure that it operates within safe voltage parameters.
Power Relay Functionality
The ECM/PCM power relay serves as a switch that provides battery voltage to the PCM when activated. It typically consists of several terminals:
- Constant Battery Voltage: Provides a steady supply of power.
- Ground Connection: Completes the circuit when activated.
- Ignition Signal: Activates the relay when the ignition switch is turned on.
- Power Output to PCM: Supplies voltage to the PCM.
- Power Relay Sense Circuit: Monitors voltage levels and sends feedback to the PCM.
If any part of this system fails—such as a defective relay, blown fuse, or faulty wiring—the PCM will set a P0690 code.
Step-by-Step Diagnosis of P0690 Code
Diagnosing a P0690 trouble code requires careful inspection and testing of various components within the electrical system. Here’s a step-by-step guide:
- Connect Diagnostic Scanner: Use an OBD-II scanner to read stored codes and freeze frame data. Take note of any additional codes present.
- Clear Codes: Clear any stored codes and take the vehicle for a test drive to see if the code returns.
- Visual Inspection:
- Check all related wiring and connectors for damage, corrosion, or loose connections.
- Inspect battery terminals and cables for signs of wear or corrosion.
- Test Fuses and Relays:
- Use a multimeter to check if fuses related to the ECM/PCM are intact.
- Test the power relay for proper operation using a digital volt/ohmmeter (DVOM).
- Check Voltage Levels:
- Measure voltage at various points in the circuit to ensure proper supply is reaching the PCM.
- If there’s no voltage at any point, trace back through the wiring harness to identify breaks or shorts.
- Inspect Ground Connections:
- Ensure that all ground connections are clean and secure. A poor ground can cause erratic behavior in electrical systems.
- Relay Testing:
- If necessary, replace the power relay with a known good unit to rule out relay failure.
- PCM Inspection:
- If all other components test fine but issues persist, consider testing or replacing the PCM as it may be malfunctioning internally.
Solution Methods for P0690 Code
Once diagnosed, addressing a P0690 trouble code involves specific repair methods based on identified issues:
Repairing or Replacing Components
- Power Relay Replacement: If testing indicates that the power relay is faulty, replace it with an OEM equivalent part.
- Fuse Replacement: Replace any blown fuses associated with the ECM/PCM circuit.
- Wiring Repairs: Repair any damaged wiring or connectors found during inspection. This may involve soldering new wires or using heat-shrink tubing for insulation.
- Battery Maintenance: Clean corroded battery terminals and ensure tight connections. Replace old batteries if they fail load tests.
Professional Help
If you are unable to diagnose or repair issues related to P0690 effectively, it’s advisable to seek assistance from a professional mechanic. They can provide advanced diagnostics using specialized equipment that might not be available to DIY mechanics.
Cost Estimates for Repairs
The cost of repairs related to a P0690 code can vary widely based on several factors:
- DIY Repairs: If you have mechanical skills, you might spend between $50-$200 on parts such as relays, fuses, and wiring materials.
- Professional Repairs: Labor costs can range from $75-$150 per hour depending on your location and shop rates. Total repair costs could be between $150-$600 depending on parts needed and labor time required.
Warnings and Recommendations
- Always disconnect your vehicle’s battery before working on electrical systems to prevent shocks or further damage.
- Use OEM parts whenever possible for replacements to ensure compatibility and reliability.
- If you are not confident in your ability to diagnose or repair electrical issues, consult with a certified mechanic rather than risking further damage to your vehicle’s systems.
Closing Paragraph
Understanding and addressing trouble codes like P0690 is essential for maintaining your vehicle’s performance and reliability. By following systematic diagnostic procedures and being aware of potential symptoms and causes, DIY mechanics can effectively troubleshoot issues related to their vehicles’ electronic control systems. Always prioritize safety and consult professionals when necessary to ensure proper repairs are made without compromising vehicle integrity.
Frequently Asked Questions About P0690
- What does error code P0690 mean?
P0690 indicates that there is an issue with high voltage detected in the ECM/PCM power relay sense circuit. - Can I drive my car with a P0690 code?
While it may be possible to drive with this code present, it could lead to starting problems or drivability issues; it’s best addressed promptly. - How do I reset a P0690 code?
You can reset a P0690 code by clearing it with an OBD-II scanner after repairs have been made. - What are common symptoms of a P0690 code?
Common symptoms include check engine light illumination, starting difficulties, and malfunctioning electrical accessories. - Is it safe to replace relays myself?
Yes, replacing relays is generally safe if you follow proper procedures; however, ensure you disconnect battery power first. - How much does it cost to fix a P0690 code?
The cost can range from $50-$600 depending on whether you do it yourself or hire a professional mechanic. - What tools do I need for diagnosing P0690?
A diagnostic scanner and digital volt/ohmmeter (DVOM) are essential tools for diagnosing this trouble code. - When should I seek professional help for P0690?
If you’re unable to diagnose or fix electrical issues after following standard procedures, it’s advisable to consult with a professional mechanic.