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Engine-Codes – GMC – P0690 2018 GMC Sierra

P0690 2018 GMC Sierra Code - Electronic Control Module Power Relay Sense Circuit High

Quick Answer

The P0690 diagnostic trouble code (DTC) on a 2018 GMC Sierra indicates a problem with the Electronic Control Module (ECM) Power Relay Sense Circuit being too high. Common causes include Faulty power relay, Loose or corroded wiring connections, ECM software glitch. 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
P0690 2018 GMC Sierra indicates Electronic Control Module Power Relay Sense Circuit High.
Common causes
Common causes include Faulty power relay, Loose or corroded wiring connections, ECM software glitch.
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 11, 2024
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Code P0690 2018 GMC Sierra Description

The P0690 diagnostic trouble code (DTC) on a 2018 GMC Sierra indicates a problem with the Electronic Control Module (ECM) Power Relay Sense Circuit being too high. The ECM is a critical component of the vehicle's engine management system, responsible for controlling various functions such as fuel delivery, ignition timing, and emissions control. The power relay sense circuit is designed to monitor the voltage level of the ECM power supply, ensuring it remains within the specified range for proper operation.

OBDII Code P0690 2018 GMC Sierra - Electronic Control Module Power Relay Sense Circuit High
P0690 2018 GMC Sierra Code - Electronic Control Module Power Relay Sense Circuit High

Common Causes of P0690 2018 GMC Sierra

  1. Faulty power relay
  2. Loose or corroded wiring connections
  3. ECM software glitch
  4. Electrical system malfunction
  5. ECM hardware failure

Symptoms of P0690 2018 GMC Sierra

  1. Engine misfires
  2. Poor fuel economy
  3. Rough idling
  4. Stalling
  5. Check engine light illuminated

How to Fix P0690 2018 GMC Sierra

  1. Perform a visual inspection of the power relay and associated wiring to check for any obvious signs of damage or corrosion.
  2. Use a multimeter to test the voltage output of the power relay to determine if it is within the specified range.
  3. Check for any loose or damaged wiring connections and repair or replace them as necessary.
  4. If the power relay is faulty, replace it with a new one that is compatible with the vehicle's ECM.
  5. Clear the DTC using a diagnostic scanner and verify that the issue has been resolved by driving the vehicle and monitoring for any recurrence of symptoms.

Cost to Fix P0690 2018 GMC Sierra

The typical repair costs for addressing the P0690 code on a 2018 GMC Sierra can range from $150 to $400, including parts and labor. However, the specific diagnosis time and labor rates at auto repair shops can vary based on factors such as location, vehicle make and model, and engine type. It's recommended to obtain local estimates for a more accurate cost assessment.

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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 P0690 2018 GMC Sierra Code

1. What does the OBDII code P0690 mean on a 2018 GMC Sierra?

P0690 indicates an issue with the Electronic Control Module (ECM) Power Relay Sense Circuit, specifically a high voltage condition has been detected.

2. What are the common symptoms of a P0690 code?

Symptoms may include the engine not starting, stalling while driving, reduced fuel efficiency, or the Check Engine Light being illuminated.

3. What causes the P0690 code to appear on a GMC Sierra?

Common causes include a faulty ECM power relay, damaged wiring or connectors in the relay circuit, a blown fuse, or a malfunctioning ECM.

4. How do I diagnose a P0690 code on my 2018 GMC Sierra?

Diagnosis involves checking the ECM power relay, inspecting the wiring and connectors for damage or corrosion, and testing the circuit voltage with a multimeter.

5. Can I drive my 2018 GMC Sierra with a P0690 code?

Driving with this code is not recommended, as it may lead to engine stalling or failure to restart, potentially leaving you stranded.

6. How do I fix a P0690 code on a GMC Sierra?

Repairs may include replacing the ECM power relay, repairing or replacing damaged wiring, replacing blown fuses, or in rare cases, replacing the ECM.

7. Is the P0690 code related to other issues in the vehicle?

Yes, it can be linked to other electrical issues, such as battery or alternator problems, which may affect the ECM power supply.

8. How much does it cost to repair a P0690 code?

Repair costs vary depending on the issue but typically range from $50 for a relay replacement to $1,000 or more if the ECM needs replacement.

9. Can a weak battery cause the P0690 code to trigger?

Yes, a weak or failing battery can contribute to power supply issues, potentially triggering this code.

10. Do I need to reprogram the ECM after fixing a P0690 code?

Reprogramming the ECM is usually not necessary unless the ECM itself is replaced or updated as part of the repair process.

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