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P27AC GMC Code - Transmission Control Solenoid Valve 6 Calibration Incorrect

Quick Answer

The P27AC GMC code indicates that there is an issue with the calibration of Transmission Control Solenoid Valve 6 in the vehicle. Common causes include Faulty Transmission Control Solenoid Valve 6, Wiring issues or electrical problems, Malfunctioning transmission control module. 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
P27AC GMC indicates Transmission Control Solenoid Valve 6 Calibration Incorrect.
Common causes
Common causes include Faulty Transmission Control Solenoid Valve 6, Wiring issues or electrical problems, Malfunctioning transmission control module.
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 10, 2024
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Code P27AC GMC Description

The P27AC GMC code indicates that there is an issue with the calibration of Transmission Control Solenoid Valve 6 in the vehicle. This component is responsible for controlling the flow of transmission fluid within the transmission system, which is crucial for the proper operation of the gears and overall performance of the vehicle. When the calibration is incorrect, it can lead to various issues such as erratic shifting, poor acceleration, and decreased fuel efficiency.

OBDII Code P27AC GMC - Transmission Control Solenoid Valve 6 Calibration Incorrect
P27AC GMC Code - Transmission Control Solenoid Valve 6 Calibration Incorrect

Common Causes of P27AC GMC

  1. Faulty Transmission Control Solenoid Valve 6
  2. Wiring issues or electrical problems
  3. Malfunctioning transmission control module
  4. Low transmission fluid level or dirty fluid
  5. Mechanical issues within the transmission system

Symptoms of P27AC GMC

  1. Erratic shifting or difficulty shifting gears
  2. Delayed engagement when shifting from park to drive or reverse
  3. Harsh or rough shifting
  4. Transmission slipping
  5. Decreased fuel efficiency

How to Fix P27AC GMC

  1. Perform a diagnostic scan to confirm the P27AC GMC code and pinpoint the exact cause of the calibration issue.
  2. Inspect the Transmission Control Solenoid Valve 6 for any signs of damage or malfunction. Replace the solenoid valve if necessary.
  3. Check the wiring and electrical connections associated with the solenoid valve for any loose connections or corrosion. Repair or replace as needed.
  4. Verify the transmission fluid level and condition. Top up the fluid or perform a transmission fluid flush if required.
  5. Reset the transmission control module and recalibrate the solenoid valve to ensure proper functionality.

Cost to Fix P27AC GMC

The typical repair costs for addressing a Transmission Control Solenoid Valve 6 calibration issue can range from $200 to $500, including parts and labor. However, the specific diagnosis time and labor rates at auto repair shops can vary depending on factors such as location, vehicle make and model, and engine type. It's recommended to inquire about local rates to get a more accurate estimate for this 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 P27AC GMC Code

1. What does the OBDII code P27AC mean on a GMC?

P27AC indicates that the Transmission Control Module (TCM) has detected an incorrect calibration or performance issue with solenoid valve 6 in the transmission.

2. What are the symptoms of the P27AC code on a GMC?

Common symptoms include rough shifting, delayed gear engagement, transmission slipping, a check engine light, and reduced fuel efficiency.

3. What causes the P27AC code to appear on my GMC?

Possible causes include a faulty transmission solenoid valve 6, TCM software issues, wiring or connector problems, or contaminated transmission fluid.

4. Can I still drive my GMC with the P27AC code?

While it may be possible to drive, it is not recommended as it can lead to further transmission damage and unsafe driving conditions.

5. How do I diagnose the P27AC code on a GMC?

A technician will typically use a scan tool to confirm the code, inspect the wiring and connectors, test the solenoid valve for functionality, and check the transmission fluid condition.

6. How much does it cost to repair the P27AC code on a GMC?

Repair costs vary but can range from $200 to $600 depending on whether the solenoid valve, wiring, or TCM requires repair or replacement.

7. Can low transmission fluid cause the P27AC code on a GMC?

Yes, low or contaminated transmission fluid can lead to solenoid calibration issues and trigger the P27AC code.

8. Does the P27AC code always mean the solenoid valve is broken?

No, it could be due to a software issue, wiring problem, or even dirty transmission fluid, not necessarily a defective solenoid.

9. How can I prevent the P27AC code from recurring on my GMC?

Regularly check and maintain proper transmission fluid levels, perform scheduled transmission servicing, and address any transmission issues promptly.

10. Do I need to reprogram the TCM to fix the P27AC code on my GMC?

In some cases, reprogramming or updating the TCM software may be necessary if the issue stems from a calibration error.

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