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Engine-Codes – GMC – P1591 GMC

P1591 GMC Code - Body Control Module Engine Speed Request Signal Message Counter Incorrect

Quick Answer

The P1591 GMC code indicates that the Body Control Module (BCM) has detected an incorrect message counter for the engine speed request signal. Common causes include Faulty engine speed sensor, Wiring or connection issues between the engine speed sensor and BCM, Defective BCM. 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
P1591 GMC indicates Body Control Module Engine Speed Request Signal Message Counter Incorrect.
Common causes
Common causes include Faulty engine speed sensor, Wiring or connection issues between the engine speed sensor and BCM, Defective BCM.
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 16, 2024
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Code P1591 GMC Description

The P1591 GMC code indicates that the Body Control Module (BCM) has detected an incorrect message counter for the engine speed request signal. The BCM plays a crucial role in controlling various electrical systems in the vehicle, including lighting, power windows, and door locks. In this case, the BCM is not receiving the correct number of messages related to the engine speed request signal, which could lead to issues with engine performance and overall vehicle operation.

OBDII Code P1591 GMC - Body Control Module Engine Speed Request Signal Message Counter Incorrect
P1591 GMC Code - Body Control Module Engine Speed Request Signal Message Counter Incorrect

Common Causes of P1591 GMC

  1. Faulty engine speed sensor
  2. Wiring or connection issues between the engine speed sensor and BCM
  3. Defective BCM
  4. Software glitches or programming errors
  5. Electrical interference or signal disruption

Symptoms of P1591 GMC

  1. Engine misfires or hesitation
  2. Rough idling or stalling
  3. Difficulty starting the vehicle
  4. Malfunctioning electrical components (lights, power windows, door locks)
  5. Reduced fuel efficiency

How to Fix P1591 GMC

  1. Use a diagnostic scanner to retrieve the trouble codes and identify the specific issue causing the P1591 code.
  2. Inspect the engine speed sensor and its wiring for any damage or loose connections. Replace or repair as necessary.
  3. Check the BCM for any signs of damage or malfunction. If needed, replace the BCM with a new unit.
  4. Clear the trouble codes from the BCM's memory and perform a test drive to ensure the issue has been resolved.
  5. If the problem persists, further diagnostics may be required to pinpoint the exact cause of the incorrect message counter.

Cost to Fix P1591 GMC

The typical repair costs for addressing the P1591 GMC code can range from $200 to $500, depending on the specific cause of the issue and the parts/labour required for the repair. It's important to note that diagnosis time and labour rates at auto repair shops can vary, so it's recommended to check with local shops for a more accurate estimate. Additionally, factors such as the vehicle make and model, as well as the location of the repair shop, can also impact the overall cost of the repair.

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Information for Specific GMC Models

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 P1591 GMC Code

1. What are the common symptoms of OBDII code P1591 in a GMC vehicle?

- Common symptoms include issues with starting the vehicle, engine stalling, poor engine performance, and illuminated warning lights on the dashboard.

2. What does the OBDII code P1591 indicate in a GMC vehicle?

- This code indicates that the Body Control Module (BCM) has detected an incorrect engine speed request signal message counter.

3. What are some possible causes of OBDII code P1591 in a GMC vehicle?

- Possible causes include a faulty BCM, wiring or connection issues between the BCM and the engine control module (ECM), a malfunctioning ECM, or a software-related issue.

4. How can I diagnose the cause of OBDII code P1591 in my GMC vehicle?

- A thorough inspection of the BCM, ECM, and related wiring is recommended. Using a diagnostic scanner to retrieve freeze frame data can also help pinpoint the issue.

5. Can I still drive my GMC vehicle with OBDII code P1591 present?

- It is not recommended to drive the vehicle with this code present, as it can lead to further engine performance issues or potential stalling while driving.

6. How can I repair OBDII code P1591 in my GMC vehicle?

- Repair options may include repairing or replacing faulty wiring, replacing the BCM or ECM if necessary, and performing any software updates recommended by the manufacturer.

7. Is it possible to reset OBDII code P1591 in a GMC vehicle using a diagnostic tool?

- Yes, a diagnostic tool can be used to clear the code after the underlying issue has been diagnosed and repaired.

8. Are there any DIY tips for troubleshooting OBDII code P1591 in a GMC vehicle?

- DIY tips may include checking for loose or damaged wiring connections, ensuring proper grounding of the BCM and ECM, and verifying the integrity of related fuses.

9. How long does it typically take to repair OBDII code P1591 in a GMC vehicle?

- The repair time can vary depending on the exact cause of the code, but it may take anywhere from a few hours to a full day to diagnose and repair the issue.

10. Can OBDII code P1591 in a GMC vehicle cause any long-term damage if left unaddressed?

- Ignoring this code can potentially lead to further damage to the engine or other components, so it is advisable to address it promptly to prevent any long-term issues.

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