Error Code P0688: What It Means & What To Do?

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The trouble code P0688 can be explained as ECM/PCM Power Relay Sense Circuit Open. This diagnostic fault code is a generic powertrain code, which means that it would apply to the OBD-II equipped vehicles. The specific repair steps can vary as it depends upon the vehicle make and model. One thing which you must keep in mind that its symptoms as well as causes would surely vary as it depends upon a number of things. The ECM/PCM power relay sense circuit is being monitored by the engine control module. This trouble code would be set by the ECM when the ECM/PCM Power Relay Sense Circuit signal would not be as per the specifications set by the manufacturer.

If there is storage of P0688 fault code, then it would mean that the powertrain control module has detected some abnormality in the relay which supplies it with voltage. This specific error code would be stored when the power relay sensor circuit voltage would exceed the maximum allowable parameter.

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

• The car battery might weak
• There might be low voltage while cranking
• Quirks in the engine control module (ECM) power relay
• ECM power relay harness might be unlocked
• ECM power relay circuit bad electrical connection
• The ECM fuse might be blown
• Defective ECM

1. Oil Pressure Gauge - It is the oil pressure gauge which reduces the wear of engine parts and ensures that the car engine does not get too and should continue to run smoothly. When you are inspecting the oil pressure gauge, then you must keep in mind that the pressure would read higher during cold weather because of higher thickness of the oil. Visit us to buy best quality oil pressure gauge online.
2. Engine Control Module - ECM faults are rare but can be a big problem as faulty ECM will cause wrong vehicle operations and can also result in wrong OBD codes getting stored in the system which can also cause misdiagnosis. Thus, replace faulty ECM components now!
3. Car Battery - The car battery can also be at fault and might have the problem of overcharging and fast discharging. This can cause increased temperatures and can also affect the functioning of various sensors like the speed sensor, temperature sensor and many more. Thus, replace faulty car battery today!
4. Electronic Control Unit - The ECU coordinates with the temperature sensor to control the blower fan for keeping the battery temperatures under control. So, replace faulty ECU components now!
5. Ignition Coil - If the backfiring is caused by your automobile, then it might indicate the symptoms of the ignition coil failure in its early stages. Car backfiring would start occurring when the unused fuel in the combustion cylinders of the engine leaves through the exhaust pipe. It would be nice if you get it replaced on time.
6. Powertrain Control Module - Check for PCM error which might be due to circuit faults that might require complete replacement and reprogramming. Replace it now!
7. Diagnostic Tool - In order to detect the error, one needs high grade diagnostic tools. Visit us today to grab amazing deals.

It is vital to know the symptoms of an issue as only then you would be able to solve the problem. So that’s why we have listed out some major symptoms of OBD Code P0688 here:

Common Symptoms

• Appearance of the service engine soon light
• There might be no symptoms other than a stored code
• Issues in starting the car engine
• Issues related to engine stalling
• Automobile might not start at all

Looking out for some ways with the help of which you can correct this fault code? Then you have arrived at the correct place. We are here to help you out, so you must check out the steps mentioned below as follows:

• Rehabilitate the defaults in the ECM/PCM relay
• Recondition the non-functioning electrical wires and related connectors
• Make sure to mend the faulty ECM
• It is essential to restore the flawed fuses
• Repair or replace the quirky battery
• It is necessary to perform proper service of the unsound connections
• The car battery should be fully charged
• Adjust the flawed battery cables
• All the codes should be cleared up and the vehicle should be taken out for a test drive

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

• First of all you must use an OBD-II scanner to check for a stored P0688 trouble code
• Carefully inspect for loose or corroded battery cables and cable ends
• Inspect that the battery is fully charged
• After that the battery load test should be performed
• Then the battery starting/charging system test should be performed
• All the damaged fuses should be carefully inspected
• Examine the system fuses
• Visually examine the wiring and associated electrical connectors for signs of damage or corrosion
• Unplug the ECM/PCM relay connector
• Inspect the associated circuits for voltage and ground signals

Common Mistakes When Diagnosing The P0688 Code

As replacing a vehicle’s ECM/PCM requires reprogramming, so that’s why it is recommended to be sure to check and repair all other possible symptoms and issues that might cause a stored P0688 code.

P0689 - ECM/PCM Power Relay Sense Circuit Low

P0690 - ECM/PCM Power Relay Sense Circuit High