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P0689 2018 GMC Sierra Code - Electronic Control Module Power Relay Sense Circuit Low

Quick Answer

The P0689 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the Electronic Control Module (ECM) Power Relay Sense Circuit being low. Common causes include Faulty power relay, Damaged wiring or connectors in the power relay sense circuit, Malfunctioning ECM. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P0689 2018 GMC Sierra indicates Electronic Control Module Power Relay Sense Circuit Low.
Common causes
Common causes include Faulty power relay, Damaged wiring or connectors in the power relay sense circuit, Malfunctioning ECM.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
What is this?
Table of contents Created and updated by William Orellana on Sep 17, 2024
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Code P0689 2018 GMC Sierra Description

The P0689 diagnostic trouble code (DTC) for a 2018 GMC Sierra indicates a problem with the Electronic Control Module (ECM) Power Relay Sense Circuit being low. The ECM is a crucial component of the vehicle's engine management system, responsible for controlling various functions such as fuel injection, ignition timing, and emissions. The power relay sense circuit is designed to monitor the voltage level of the power relay that supplies power to the ECM. When the voltage level is detected to be low, the ECM triggers the P0689 code to alert the driver or technician of a potential issue.

OBDII Code P0689 2018 GMC Sierra - Electronic Control Module Power Relay Sense Circuit Low
P0689 2018 GMC Sierra Code - Electronic Control Module Power Relay Sense Circuit Low

Common Causes of P0689 2018 GMC Sierra

  1. Faulty power relay
  2. Damaged wiring or connectors in the power relay sense circuit
  3. Malfunctioning ECM
  4. Poor electrical connection
  5. Corrosion or moisture in the electrical system

Symptoms of P0689 2018 GMC Sierra

  1. Engine stalling or rough idling
  2. Difficulty starting the vehicle
  3. Reduced fuel efficiency
  4. Hesitation during acceleration
  5. Illumination of the Check Engine Light

How to Fix P0689 2018 GMC Sierra

  1. Begin by conducting a thorough inspection of the power relay, wiring, and connectors to identify any visible damage or corrosion.
  2. Test the power relay using a multimeter to check for proper voltage output.
  3. Check the ECM for any signs of damage or malfunction and ensure all connections are secure.
  4. Repair or replace any damaged components, such as the power relay, wiring, connectors, or ECM, as needed.
  5. Clear the DTC and perform a test drive to verify that the issue has been resolved.

Cost to Fix P0689 2018 GMC Sierra

The typical repair costs for addressing the P0689 code on a 2018 GMC Sierra can vary depending on the specific cause of the issue and the extent of the repairs needed. In general, the cost of parts such as a new power relay or ECM can range from $100 to $500, while labor costs can range from $100 to $300. Overall, the total repair cost for this issue may fall between $200 and $800. It is important to note that diagnostic time and labor rates at auto repair shops can vary, so it is advisable to obtain quotes from multiple sources to ensure a competitive price.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P0689 2018 GMC Sierra Code

1. What are common symptoms of OBDII code P0689 in a 2018 GMC Sierra?

Symptoms may include difficulty starting the engine, engine stalling, poor vehicle performance, and the illumination of the check engine light.

2. What does the OBDII code P0689 for a 2018 GMC Sierra indicate?

The code signifies a problem with the Electronic Control Module (ECM) Power Relay Sense Circuit being too low, affecting the ECM's ability to function properly.

3. What are possible causes of the Electronic Control Module Power Relay Sense Circuit Low code in a 2018 GMC Sierra?

Causes may include a faulty ECM power relay, damaged wiring or connections in the circuit, a malfunctioning ECM, or issues with the power supply to the ECM.

4. How can I diagnose the cause of the P0689 code in my 2018 GMC Sierra?

Diagnosis typically involves checking the ECM power relay, inspecting the wiring and connections for damage, testing the ECM for proper function, and ensuring the power supply to the ECM is stable.

5. What are the repair options for fixing the Electronic Control Module Power Relay Sense Circuit Low issue in a 2018 GMC Sierra?

Repair options may include replacing the ECM power relay, repairing or replacing damaged wiring or connections, testing and potentially replacing the ECM, and ensuring a stable power supply to the ECM.

6. Can I drive my 2018 GMC Sierra with the P0689 code present?

It is not recommended to drive your vehicle with the P0689 code active, as it can lead to engine performance issues and potential stalling, posing a safety risk.

7. How much does it typically cost to repair the ECM Power Relay Sense Circuit Low issue in a 2018 GMC Sierra?

Costs can vary depending on the specific cause of the problem, but repairs for this code may range from $200 to $600, including parts and labor.

8. Is it possible to reset the P0689 code in a 2018 GMC Sierra without fixing the underlying issue?

While you can clear the code with an OBDII scanner, it is crucial to address the root cause of the problem to prevent further issues and ensure proper vehicle operation.

9. How long does it take to repair the Electronic Control Module Power Relay Sense Circuit Low problem in a 2018 GMC Sierra?

The repair time can vary based on the specific repair needed, but it typically takes a few hours to a full day to diagnose and fix the issue properly.

10. Can a DIY enthusiast fix the P0689 code in a 2018 GMC Sierra themselves?

While some may have the skills to address simpler aspects like checking connections or relays, diagnosing and repairing the ECM or wiring issues may require professional expertise and specialized tools.

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