P2799 Code: Complete DIY Repair Guide

The P2799 trouble code is a diagnostic trouble code (DTC) that indicates an issue with the auxiliary transmission fluid pump control circuit. Specifically, it signifies that the control circuit for the auxiliary transmission fluid pump is experiencing a high voltage condition. This code can lead to a range of transmission-related issues, affecting vehicle performance and drivability. Understanding this code is crucial for vehicle owners and DIY mechanics, as it can help in diagnosing and rectifying problems related to the transmission system.

Symptoms of P2799 Code

Common Symptoms

• Check Engine Light: The most immediate indication of a P2799 code is the illumination of the check engine light.
• Transmission Overheating: You may notice that your transmission is overheating, which can lead to further damage if not addressed.
• Diminished Shifting Efficiency: The vehicle may experience delayed or harsh shifting, affecting overall drivability.
• Sluggish Acceleration: A noticeable decrease in acceleration response may occur, particularly during gear changes.

Technical Explanation

The P2799 code is related to the auxiliary transmission fluid pump, which is responsible for maintaining adequate fluid pressure within the transmission system. This pump operates based on signals from the Powertrain Control Module (PCM), which monitors various parameters including vehicle speed and temperature. When the PCM detects a high voltage condition in the control circuit of the auxiliary pump, it triggers the P2799 code.

The auxiliary transmission fluid pump plays a vital role in ensuring smooth operation by providing necessary fluid pressure to components such as the torque converter and transmission cooler. If this system fails, it can lead to inadequate lubrication and cooling of the transmission, resulting in severe damage over time.

Step-by-Step Diagnosis

1. Initial Scan: Use an OBD-II scanner to confirm the presence of the P2799 code along with any other related codes.
2. Visual Inspection:

• Check all wiring and connectors related to the auxiliary transmission fluid pump for signs of damage or corrosion.
• Inspect fuses associated with the transmission system for continuity.

1. Voltage Testing:

• Using a multimeter, test for proper voltage at the auxiliary pump connector while the ignition is on.
• Compare readings against manufacturer specifications.

1. Pump Functionality Test:

• If safe to do so, apply direct power to the auxiliary pump to see if it operates correctly.
• Listen for unusual noises that could indicate internal failure.

1. PCM Assessment:

• If all other components check out, consider testing or reprogramming the PCM as it may be malfunctioning.

Solution Methods

Common Repairs

• Replace Faulty Pump: If testing indicates that the auxiliary transmission fluid pump is non-functional, replacement is necessary.
• Repair Wiring Issues: Fix any damaged wiring or connectors found during inspection. Ensure all connections are secure and free from corrosion.
• Check Fuses: Replace any blown fuses related to the transmission system.
• Reprogram/Replace PCM: If no other issues are found, consider reprogramming or replacing the PCM if it’s determined to be faulty.

Cost Estimates

• Auxiliary Pump Replacement: $300 – $800 depending on vehicle make and model.
• Wiring Repairs: $100 – $300 depending on severity and location of damage.
• Fuses/Connectors Replacement: Typically under $50 for parts and labor.
• PCM Reprogramming/Replacement: $150 – $400 for reprogramming; $500 – $1,500 for replacement depending on vehicle complexity.

Warnings and Recommendations

• Always ensure that you disconnect the battery before working on electrical components to prevent shorts or shocks.
• If unsure about any step in diagnosing or repairing issues related to P2799, consult a professional mechanic.
• Regular maintenance of your vehicle’s transmission system can prevent issues such as those indicated by P2799 from occurring in the first place.

Closing Paragraph

Understanding and addressing a P2799 trouble code is essential for maintaining your vehicle’s performance and longevity. By following this guide, DIY mechanics can effectively diagnose and rectify issues related to their auxiliary transmission fluid pump control circuit. Remember that while some repairs can be tackled at home, seeking professional assistance is always advisable when in doubt about complex electrical systems.

Frequently Asked Questions About P2799

• What does error code P2799 mean?
  P2799 indicates a high voltage condition in the auxiliary transmission fluid pump control circuit.
• What are common symptoms of P2799?
  Common symptoms include check engine light illumination, overheating transmission, and diminished shifting efficiency.
• Can I drive my car with a P2799 code?
  While it may be drivable initially, continued operation can lead to severe transmission damage; repairs should be made promptly.
• How do I reset a P2799 code?
  The code can be cleared using an OBD-II scanner after repairs are made; however, ensure that underlying issues are resolved first.
• Is P2799 a serious problem?
  Yes, if left unaddressed, it can result in significant damage to your vehicle’s transmission system.
• How much does it cost to fix a P2799 code?
  The cost varies widely depending on repairs needed but typically ranges from $100 to over $1,500.
• What tools do I need to diagnose P2799?
  A basic OBD-II scanner and multimeter are essential tools for diagnosing this trouble code.
• When should I seek professional help for P2799?
  If you’re unable to identify or resolve issues after initial diagnostics, it’s advisable to consult a professional mechanic.