P0689 Fault Code

ECM/PCM Power Relay Sense Circuit Low

• What does that mean?
• Symptoms
• Causes
• Solutions

The P0689 fault code refers to an issue with the ECM/PCM Power Relay Sense Circuit. This circuit plays a crucial role in ensuring that the engine control module (ECM) or powertrain control module (PCM) receives the correct voltage from the power relay. A low voltage reading indicates a potential fault in the power supply or the circuit itself.

• The ECM/PCM power relay helps to power the module when the ignition is turned on.
• A low sense circuit voltage can prevent the ECM/PCM from operating properly, leading to various performance issues.

What are the symptoms of the P0689 code?

When the P0689 code is triggered, you may experience a few noticeable symptoms:

• Engine may not start at all or has trouble starting.
• Poor engine performance, possibly stalling or misfires.
• Various warning lights illuminating on the dashboard, such as the check engine light.
• Inconsistent electrical components or features, such as difficulty with starting systems or erratic behavior of other modules.

What causes the P0689 code?

Several factors can lead to a low reading in the ECM/PCM Power Relay Sense Circuit:

• Faulty power relay itself that may be malfunctioning or stuck.
• Corroded or damaged wiring and connectors in the circuit.
• A blown fuse affecting the power relay.
• Issues with the ECM/PCM that cause it to misinterpret voltage readings.

How to fix P0689?

To resolve the P0689 fault code, several steps can be taken:

• Inspect the power relay for proper functionality; replace it if necessary.
• Check wiring and connectors for any signs of damage, corrosion, or loose connections, and repair as needed.
• Test the fuses related to the power relay and replace any that are blown.
• Use a diagnostic tool to clear the fault code after completing the necessary repairs, and perform a test drive to ensure the issue is resolved.