P0685 OBD Error Code: Problem & Solutions

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If you are experiencing unusual response of the throttle, lack of power forms the car engine, impact on the fuel economy, engine stalling and hard starts and frequent illumination of the Check Engine Light, it might be an indication of the OBD Code P0685 error.

P0685 is the fault code for ECM/PCM Power Relay Control Circuit /Open

When OBD code P0685 is stored in the powertrain control module (PCM), it means that a low or no-voltage condition has been detected in the circuit which supplies the PCM with battery voltage. The PCM (powertrain control module) receives data about the vehicle’s operating conditions from various areas in the system. In order to work properly, the PCM is supplied with power by a relay, which uses a battery voltage signal, a ground signal, and an ignition switch input signal. The voltage in the relay coil control circuit is normally low. If you see trouble code P0685, it means that the PCM’s fault detection circuit has detected voltage from the relay that measures above the normal parameters – above 4.6 volts with the key turned on.

What causes this problem with the ECM/PCM Power Relay Control Circuit Open?

• Weak battery
• Low voltage while cranking
• Faulty Powertrain Control Module (ECM) power relay
• PCM power relay harness is open or shorted
• PCM power relay circuit poor electrical connection
• Blown PCM fuse
• Faulty PCM

1. Engine Control Module - OBD Error Code P0685 can also be due to faulty ECMs. It’s better to get the faulty electricals replaced as soon as possible.
2. Powertrain Control Module - PCM problem can lead the wrong OBD code flashing and getting stored in the system. Thus, replace all faulty Powertrain related parts with us.
3. Diagnostic Tool - In order to detect the error, one needs high grade diagnostic tools. Visit us today to buy quality diagnostic tools.
4. Ignition Switch - Faulty ignition switch can also cause start-up problems and must be replaced, if found faulty.
5. Car Battery & Cables - Replace faulty cables and parts for proper functioning of starting and charging system. Buy new cables and parts from us.
6. ECU Fuse - Replacing faulty fuses are easy and quick way to solve any problem in relation to a component. Buy new engine control unit fuses now!

Our main motive is to achieve customer satisfaction as for us our customers are everything and that’s why we will help you to diagnose P0685 code by mentioning some major symptoms below:

Common Symptoms

• Check Engine Light On
• Engine Hard Starts and Stalling
• Engine Going in Limp Mode
• Reduced Throttle Response and Acceleration

If you wish to correct this fault code, then you have to follow certain steps. Correcting a problem needs your careful attention. Here are some ways with the help of which you will be able to correct the OBD Code P0685:

• Shorts or bad terminals or connections repairs
• Powertrain control module relay replacement
• Under hood junction block replacement (fuse box)
• Bad Battery cables and/or connectors replacement
• Fuse replacement

However, if you face any issue then we have stocked a wide range of best priced PCM Power Relay, ECM Relay, PCM Relay, Blown Fuse, Ignition Switch, Battery Cable, PCM and more to help you out in fixing your car.

Here are some steps which you should follow in order to diagnose this P0685 fault code:

• The first step in diagnosing any trouble code is typically to record the stored codes and freeze frame data using an OBD-II scanner.
• Any other codes that come up should be investigated and fixed in the order in which they happened. The vehicle will then be retested to make sure the P0685 code returns (if not, it may be an intermittent condition, which can make diagnostics more complicated).
• Next, the technician will remove the powertrain relay and test the control circuit to determine if it is functioning properly.
• Other terminals and connectors may also be tested to locate the interruption in the power source. The mechanic will also perform a visual inspection of the battery cables, as corrosion or loose connections can affect the PCM/ECM relay.
• Once all of these tests and any necessary repairs have been completed, the vehicle will be tested to see if it runs and if the code returns. If the problem hasn’t been solved, the PCM itself could be faulty.

Common Mistakes When Diagnosing the P0685 Code

It’s easy to rush to judgement and simply replace the PCM, when in fact this isn’t usually the problem and is a very costly repair. Corroded battery cables or a loose connection often cause issues with the PCM relay, so these should be a routine part of the inspection