Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
This code means that the car's computer isn't getting the power it needs because something in the power path is broken or not connected.
The car's Engine Control Module (ECM) or Powertrain Control Module (PCM) relies on a relay to supply it with power. If this relay or its circuit is open or not working, the ECM/PCM won't function properly.
The P0685 code indicates that the ECM/PCM Power Relay Control Circuit is open. This means that the relay responsible for supplying power to the ECM/PCM is not completing the circuit, possibly due to a fault in the relay, wiring, or connectors.
• Engine may not start
• Check Engine Light illuminated
• Intermittent engine stalling
• Poor engine performance
• No communication with the ECM/PCM
• Faulty ECM/PCM power relay
• Open or shorted wiring in the power relay circuit
• Corroded or damaged connectors
• Blown fuse
• Faulty ECM/PCM
ECM: Engine Control Module
PCM: Powertrain Control Module
Relay: An electrically operated switch
• Inspect the ECM/PCM power relay for damage or faults.
• Check the wiring and connectors for continuity and damage.
• Test the relay circuit for proper voltage and ground.
• Inspect and test the fuses related to the ECM/PCM power supply.
• Use a scan tool to check for additional codes and ECM/PCM communication.
• Replace the faulty ECM/PCM power relay.
• Repair or replace damaged wiring or connectors.
• Replace blown fuses.
• Repair or replace the ECM/PCM if necessary.
• Multimeter
• OBD-II scanner
• Relay tester
• Basic hand tools
$100 - $300
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect electrical connections for corrosion.
• Ensure all fuses are in good condition.
• Perform routine maintenance checks on the vehicle's electrical system.
Electrical Issue
• Avoid driving the vehicle until the issue is resolved to prevent further damage.
• Consult with a professional mechanic for a thorough diagnosis.
Check with the vehicle manufacturer for warranty coverage on electrical components.
The P0685 code has been commonly reported in vehicles with aging electrical systems or those exposed to harsh environments.
High – This issue can prevent the vehicle from starting or cause it to stall unexpectedly.
Driving with this code may lead to unexpected engine shutdowns, posing safety risks. Address the issue promptly.
• Engine off and key in the ON position.
• Battery fully charged.
The ECM/PCM power relay is typically located in the vehicle's fuse box or relay panel under the hood.
Q: Can I drive my car with a P0685 code?
A: It's not recommended as the engine may stall or fail to start, posing safety risks.
Q: How do I reset the P0685 code?
A: After repairs, use an OBD-II scanner to clear the code. Ensure the issue is fixed to prevent recurrence.
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