P1747 Code: Complete DIY Repair Guide

The P1747 trouble code is a diagnostic trouble code (DTC) that indicates a problem with the Electric Pressure Control (EPC) solenoid circuit in an automatic transmission. This code can lead to significant driveability issues, including poor shifting, slipping, or even complete transmission failure if not addressed promptly. Understanding the P1747 code is crucial for vehicle owners and DIY mechanics, as it can help diagnose and resolve transmission-related issues effectively.

Symptoms of P1747 Code

When the P1747 code is triggered, several symptoms may manifest, indicating a potential issue with the transmission:

• Flashing Check Engine Light: The check engine light may illuminate or flash, especially when the vehicle is under load.
• Poor Shifting: Drivers may experience harsh or erratic shifting, with the transmission failing to engage properly.
• Slipping Transmission: The vehicle may slip out of gear or fail to accelerate as expected.
• Overdrive Light Blinking: In some vehicles, the overdrive light may blink, indicating a transmission fault.
• Reduced Power: The vehicle may exhibit reduced power and acceleration capabilities.

Technical Explanations

The P1747 code specifically relates to the Electric Pressure Control (EPC) solenoid within the automatic transmission system. This solenoid regulates hydraulic pressure in the transmission, which is crucial for smooth shifting and overall performance. When a short circuit is detected in this circuit, it can lead to various driveability issues.

How the EPC Solenoid Works

The EPC solenoid receives signals from the Transmission Control Module (TCM) based on input from various sensors. It adjusts hydraulic pressure according to driving conditions to ensure optimal shifting performance. A malfunction in this system can cause improper pressure regulation, leading to erratic shifting and potential damage to the transmission.

Step-by-Step Diagnosis

Diagnosing a P1747 code involves several steps:

1. Scan for Codes: Use an OBD-II scanner to confirm the presence of the P1747 code and check for any related codes that may provide additional context.
2. Inspect Wiring and Connectors: Examine the wiring harness leading to the EPC solenoid for signs of damage, such as fraying or corrosion. Ensure all connectors are secure and free of dirt or moisture.
3. Test EPC Solenoid: Using a multimeter, test the resistance of the EPC solenoid. Compare your readings with manufacturer specifications to determine if it’s functioning correctly.
4. Check TCM Functionality: If no issues are found with the wiring or solenoid, inspect the TCM for faults. This may require specialized diagnostic equipment.
5. Inspect Transmission Internals: If all else fails, consider checking internal components of the transmission for wear or damage that could affect solenoid performance.

Solution Methods

Addressing a P1747 code typically involves one or more of the following solutions:

• Replace EPC Solenoid: If testing indicates that the EPC solenoid is faulty, replacing it is often necessary to restore proper function.
• Repair Wiring Harness: Any damaged wiring should be repaired or replaced to eliminate shorts or open circuits affecting solenoid operation.
• Clean Electrical Connectors: Corroded connectors should be cleaned using electrical contact cleaner to ensure good connectivity.
• Replace TCM: In cases where the TCM is determined to be faulty, replacement may be required.
• Transmission Service: If internal issues are suspected, performing a full service on the transmission—including fluid change—may help alleviate symptoms.

Cost Estimates

The cost of repairs related to a P1747 code can vary significantly based on several factors:

• EPC Solenoid Replacement: Parts typically range from $50 to $150, with labor costs adding another $100 to $200 depending on shop rates.
• Wiring Repairs: Minor repairs may cost around $50-$100, while extensive harness replacements could exceed $200.
• TCM Replacement: A new TCM can range from $200 to $600, plus labor costs for installation and programming.
• Transmission Service: A full service might cost between $150 and $300 depending on fluid type and labor involved.

Warnings and Recommendations

• Professional Help Needed: If you are unsure about diagnosing or repairing issues related to the P1747 code, it’s advisable to seek assistance from a certified mechanic.
• Avoid Driving with Code Active: Continuing to drive with an active P1747 code can lead to further damage to your transmission, resulting in more costly repairs down the line.
• Regular Maintenance: Regularly maintaining your vehicle’s transmission fluid and components can help prevent issues like those indicated by a P1747 code.

Frequently Asked Questions About P1747

• What does error code P1747 mean?
  P1747 indicates a short circuit in the Electric Pressure Control (EPC) solenoid circuit within an automatic transmission.
• What are common symptoms associated with P1747?
  Common symptoms include poor shifting performance, slipping transmission, flashing check engine light, and reduced power.
• How can I diagnose a P1747 code?
  Diagnosing involves scanning for codes, inspecting wiring and connectors, testing the EPC solenoid, and checking TCM functionality.
• What should I do if I get a P1747 code?
  If you receive this code, inspect wiring and connectors first; then test or replace the EPC solenoid as needed.
• Can I drive my vehicle with a P1747 code?
  No, driving with this code can lead to further damage; it’s best to address it promptly.
• How much does it cost to fix a P1747 code?
  The cost varies widely but can range from $50 for minor repairs up to $600 for TCM replacement.
• Is professional help necessary for P1747?
  If you lack experience with transmissions or electrical systems, seeking professional assistance is recommended.
• What vehicles are affected by P1747?
  P1747 can occur in various makes and models equipped with automatic transmissions that utilize an EPC system.

In conclusion, understanding and addressing a P1747 trouble code is vital for maintaining your vehicle’s performance and reliability. By following proper diagnostic procedures and taking corrective actions promptly, you can mitigate potential damage and ensure smooth operation of your automatic transmission.