Description of the P0689 fault code.
OBD2 Error Codes

P0689 Engine/Transmission Control Module (ECM/PCM) Power Relay Sensor Circuit Low

26.05.2022 /

P0689 – OBD-II Trouble Code Technical Description

Trouble code P0689 indicates that the engine control module (ECM) or powertrain control module (PCM) power relay control circuit voltage is too low (compared to the manufacturer's specifications).

What does the fault code mean P0689?

Trouble code P0689 indicates that the engine control module (ECM) or powertrain control module (PCM) power relay control circuit has detected too low a voltage. This means that the electrical circuit that is responsible for supplying power to these modules does not provide the required voltage level, which is specified in the manufacturer's technical specifications. It should be noted that along with the P0689 code, errors may also appear P0685, P0686, P0687, P0688 и P0690.

Fault code P0689.

Possible reasons

Possible reasons for DTC P0689:

  • Damaged or broken wires: The wires in the power relay circuit may be damaged, broken or burned, resulting in incorrect electrical contact and insufficient power.
  • Faulty power relay: The power relay itself may be defective or broken, preventing normal power supply to the engine or powertrain control modules.
  • Battery problems: Low voltage or improper battery operation may cause insufficient power through the power relay.
  • Insufficient grounding: Incorrect or insufficient grounding in the circuit can also result in insufficient power to the control modules.
  • Problems with the ignition switch: A malfunctioning ignition switch may prevent the power relay from operating properly, resulting in insufficient power to the control modules.
  • ECM/PCM problems: Defects or malfunctions in the Engine Control Module (ECM) itself or the Powertrain Control Module (PCM) can also cause the P0689 code to appear.
  • Generator malfunction: If the generator is not producing enough electricity to supply the power relay, this can also cause the P0689 code.
  • Problems with contacts and connections: Improper or oxidized contacts and connections in a circuit can create resistance, which in turn reduces the voltage in the circuit.

These causes should be considered during diagnosis and repair to determine and correct the problem causing the P0689 trouble code.

What are the symptoms of a fault code? P0689?

If DTC P0689 is present, you may experience the following symptoms:

  • Problems with starting the engine: Low voltage in the power relay circuit may cause the engine to be difficult or unable to start.
  • Loss of power: Insufficient power to the ECM or PCM may cause loss of engine power or unstable operation.
  • Unstable engine operation: Improper power supply may cause the engine to run erratically, such as shaking, shaking or jerking when driving.
  • Limitation of vehicle functions: Some vehicle functions that depend on the ECM or PCM may not operate properly or be unavailable due to insufficient power.
  • Check Engine Light Appears: Code P0689 activates the Check Engine light on the dashboard, indicating problems with the electrical system.
  • Loss of electrical components: Some vehicle electrical components, such as lights, heaters, or climate controls, may work less efficiently or fail altogether due to insufficient power.
  • Speed ​​Limit: In rare cases, the vehicle may go into limited speed mode due to electrical system problems caused by code P0689.

How to diagnose a fault code P0689?

To diagnose DTC P0689, follow these steps:

  1. Checking the battery: Using a multimeter, check the battery voltage. Make sure the voltage is within the normal range and the battery is charged. Also check the condition of the terminals and wires for corrosion or poor contact.
  2. Checking wiring and connections: Inspect the wires from the power relay to the ECM/PCM for damage, breaks, or burns. Check connections and contacts for oxidation or poor contact.
  3. Checking the power relay: Check the operation of the power relay. Make sure it functions correctly and provides stable power to the ECM/PCM.
  4. Grounding check: Verify that the ground on the power relay control circuit is operating correctly and provides a reliable ground for system operation.
  5. Checking the signal from the ignition switch: Check if the signal from the ignition switch reaches the power relay. If necessary, check the condition and functionality of the ignition switch itself.
  6. Using the Diagnostic Scanner: Connect a diagnostic scan tool to the OBD-II port and read trouble codes to get more information about the problem and system status.
  7. Carrying out voltage tests: Using a multimeter, measure the voltage at various points in the control circuit to check that it is stable and within specifications.
  8. Additional tests and checks: Perform additional tests, such as checking the operation of the alternator and other charging system components, if necessary.

After diagnosing and identifying the possible cause of the P0689 code, you can begin to resolve the problem by repairing or replacing the faulty components. It is important to carry out diagnostics carefully and systematically to avoid mistakes and correctly determine the cause of the problem. If you do not have experience in diagnosing and repairing vehicles, it is recommended that you contact a professional auto mechanic or auto repair shop for assistance.

Diagnostic errors

When diagnosing DTC P0689, the following errors may occur:

  • Misinterpretation of data: Misunderstanding of diagnostic information may lead to incorrect identification of the cause of the problem.
  • Skipping important steps: Skipping certain diagnostic steps or doing them in the wrong order may result in missing key factors affecting the problem.
  • Faulty diagnostic tools: Using faulty or uncalibrated diagnostic tools may result in inaccurate results and incorrect conclusions.
  • Incorrect connection: Incorrect connection to the system under test or incorrect selection of the diagnostic port may prevent the data from being read correctly.
  • Skip additional checks: Some causes of the problem may be hidden or not obvious at first glance, so skipping additional checks may result in an undiagnosed or incompletely diagnosed problem.
  • Incorrect interpretation of error codes: Some error codes may be related or have common causes, so misinterpreting or ignoring additional error codes may result in an incomplete diagnosis.

To successfully diagnose DTC P0689, it is important to follow the recommended procedures and techniques.

How serious is the fault code? P0689?

Trouble code P0689 is quite serious because it indicates problems in the vehicle's electrical system that can affect the operation of key components such as the engine control module (ECM) or powertrain control module (PCM). Low voltage in the power relay control circuit can cause serious problems such as:

  • Problems with starting the engine: Low voltage may make starting the engine difficult or impossible.
  • Loss of power and unstable engine operation: Insufficient ECM or PCM power can result in loss of engine power, rough operation, or even cylinder misfire, which will significantly reduce vehicle performance and efficiency.
  • Functionality limitation: Some vehicle functions that depend on the ECM or PCM may not operate properly or be unavailable due to insufficient power.
  • Damage to components: Low voltage can cause damage to other electrical system components, as well as overheating or damage to the ECM or PCM itself.

Due to these possible consequences, trouble code P0689 requires serious attention and immediate resolution of the problem. Diagnosis and repairs must be made as soon as possible to avoid further problems and ensure safe and reliable operation of the vehicle.

What repair will help eliminate the code? P0689?

Resolving the P0689 trouble code depends on the specific cause of the problem, there are several potential repair steps that may help:

  1. Replacing or repairing damaged wires and connections: If damaged or broken wires are found, they should be replaced or repaired. Make sure the connections are in good condition and ensure a good electrical connection.
  2. Replacing the power relay: If the power relay is faulty, you need to replace it with a new one that is compatible with your vehicle. Make sure the new relay meets the manufacturer's specifications.
  3. Battery check and maintenance: Make sure the battery is charged and working properly. Replace the battery or perform service if necessary.
  4. Checking and repairing the ignition switch: Check the condition and functionality of the ignition switch. Replace or repair it if necessary.
  5. Check and, if necessary, replace the ECM/PCM: If all of the above steps do not help, the problem may be due to a problem with the Engine Control Module (ECM) itself or the Powertrain Control Module (PCM). In this case, the ECM/PCM may need to be replaced or repaired.
  6. Additional diagnostic tests and repairs: Additional diagnostic tests and checks may need to be performed to pinpoint the cause of the problem and resolve it.

It is important to carry out repairs taking into account the specific cause of the problem identified as a result of diagnosis. If you do not have the experience or skills to perform the repair yourself, it is recommended that you contact a qualified automotive technician or service center for diagnosis and repair.

How to Diagnose and Fix P0689 Engine Code - OBD II Trouble Code Explain

P0951 – Brand-specific information

Trouble code P0689 can be applied to different brands of cars, a list of several brands of cars with their meanings for the P0689 code:

This is just a small list of vehicle brands that may experience trouble code P0689. It is important to note that the causes and solutions to this problem may vary slightly depending on the specific model and year of the vehicle.

One comment

  • Gomes snakes

    10.11.2023 at 11:58

    Code P0689 is accompanying with error code p0682. Code p0682 is permanent and does not erase

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