Easy one-page printout for the garage or repair shop
This summary uses the existing diagnostic information shown in full below.
The car's computer isn't getting enough power because of a problem with the switch that turns it on.
The P0686 code indicates that the Engine Control Module (ECM) or Powertrain Control Module (PCM) is not receiving the correct voltage from the power relay circuit.
This code is set when the ECM/PCM detects a low voltage condition in the power relay control circuit. This relay is responsible for supplying power to the ECM/PCM, and a low voltage condition can prevent the module from operating correctly.
• Engine may not start
• Check Engine Light is on
• Poor engine performance
• Faulty ECM/PCM power relay
• Blown fuse in the power relay circuit
• Open or shorted wiring in the power relay control circuit
ECM: Engine Control Module
PCM: Powertrain Control Module
Relay: An electrical switch that opens and closes under the control of another electrical circuit
• Check the ECM/PCM power relay for proper operation.
• Inspect the fuses related to the power relay circuit.
• Examine the wiring and connectors for any signs of damage or corrosion.
• Replace the faulty ECM/PCM power relay.
• Replace any blown fuses in the circuit.
• Repair or replace damaged wiring or connectors.
• Multimeter
• Relay tester
• Basic hand tools
$100 - $300
Moderate
• Ford F-150
• Chevrolet Silverado
• Toyota Camry
• Regularly inspect fuses and relays.
• Keep electrical connections clean and free of corrosion.
• Perform routine maintenance checks on the vehicle's electrical system.
Electrical Circuit Issue
• If the engine doesn't start, check the fuses and relays first.
• Consult with a professional mechanic for a thorough diagnosis.
Check with your vehicle manufacturer for warranty coverage on electrical components.
This code has been commonly reported in vehicles with aging electrical systems, often due to wear and tear on relays and wiring.
High – This issue can prevent the vehicle from starting, requiring immediate attention.
Driving with this code can lead to unexpected engine shutdowns, which may be unsafe.
• Vehicle ignition in the ON position
• Battery fully charged
The ECM/PCM power relay is typically located in the fuse box under the hood or inside the vehicle.
Q: Can I drive with a P0686 code?
A: It's not recommended to drive with this code as it can cause the engine to stop unexpectedly.
Q: How do I reset the Check Engine Light after fixing the issue?
A: You can use an OBD-II scanner to clear the code, or the light may turn off automatically after several driving cycles if the issue is resolved.
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