The P1739 trouble code is a diagnostic trouble code (DTC) that indicates an issue with the 3rd clutch pressure switch circuit in automatic transmission systems. This code is typically triggered when the Powertrain Control Module (PCM) detects that the readings from the 3rd clutch pressure switch are outside of the expected range. This can lead to various transmission performance issues, including harsh shifting, slipping, or even complete failure to engage gears. Understanding this code is crucial for vehicle owners and DIY mechanics as it can help prevent further damage to the transmission system.
| P1739 Code Meaning | P1739 Code Common Causes |
|---|---|
| Problem in 3rd Clutch Pressure Switch Circuit | Faulty 3rd clutch pressure switch |
| Incorrect pressure readings from the switch | Wiring issues or short circuits in the circuit |
| Transmission control module (TCM) malfunction | Fluid level low or contaminated transmission fluid |
| Internal transmission faults | Bad electrical connections or corroded terminals |
Symptoms of P1739 Code
When the P1739 code is present, drivers may experience several symptoms that can indicate a problem with their vehicle’s transmission system:
- Check Engine Light: The most obvious symptom is the illumination of the check engine light on the dashboard.
- Harsh Shifting: Drivers may notice that their vehicle shifts roughly between gears, particularly when shifting into or out of third gear.
- Slipping Gears: The transmission may slip out of gear unexpectedly, causing a loss of power.
- Delayed Engagement: There may be a noticeable delay when shifting from park to drive or reverse.
- Increased RPMs: The engine may rev higher than normal without corresponding acceleration, indicating a potential issue with gear engagement.
Technical Explanation
The P1739 code specifically refers to issues within the 3rd clutch pressure switch circuit. This switch is responsible for monitoring hydraulic pressure within the transmission and relaying this information back to the PCM. If the PCM detects that the signal from this switch is outside acceptable parameters, it triggers the P1739 code.
How the System Works
In automatic transmissions, hydraulic pressure is essential for engaging and disengaging gears. The 3rd clutch pressure switch plays a critical role in maintaining this hydraulic balance. If there is an issue with this switch or its circuit, it can lead to improper gear engagement and various performance issues.
Step-by-Step Diagnosis
Diagnosing a P1739 code involves several steps to pinpoint the exact cause of the problem:
- Read Diagnostic Codes: Use an OBD-II scanner to confirm that P1739 is present and check for any additional codes that may provide further insight into related issues.
- Visual Inspection: Inspect wiring and connectors associated with the 3rd clutch pressure switch for any signs of damage, corrosion, or loose connections.
- Check Transmission Fluid: Ensure that the transmission fluid is at the correct level and in good condition (not burnt or contaminated).
- Test Voltage at Switch: With the ignition on but the engine off, check for voltage at the 3rd clutch pressure switch connector. You should see battery voltage (approximately 12V). If not, there may be an issue with wiring or the PCM.
- Resistance Testing: Disconnect the switch and measure resistance across its terminals. A properly functioning switch should show high resistance (open circuit). A low resistance reading indicates a faulty switch that needs replacement.
- Check PCM Functionality: If all else checks out, there may be an issue with the PCM itself, which might require reprogramming or replacement.
Solution Methods
Once you have diagnosed the issue causing the P1739 code, you can proceed with repairs:
Replace Faulty Components
- 3rd Clutch Pressure Switch: If testing indicates that this component is faulty, it should be replaced. This is often a straightforward job for DIY mechanics and can typically be done without removing major components.
Repair Wiring Issues
- Wiring and Connectors: If damaged wiring or corroded connectors are found during inspection, these should be repaired or replaced to ensure proper electrical flow.
Fluid Maintenance
- Transmission Fluid Change: If fluid contamination is suspected, performing a fluid change may resolve shifting issues and improve overall transmission performance.
Professional Assistance
If you are not comfortable performing these repairs yourself or if issues persist after addressing these components, it’s advisable to seek help from a certified mechanic who has experience with automatic transmissions.
Cost Estimates
The cost of addressing a P1739 code can vary widely depending on what repairs are necessary:
- 3rd Clutch Pressure Switch Replacement: Typically ranges from $50 to $200 for parts and labor depending on vehicle make and model.
- Wiring Repairs: Costs can vary significantly based on the extent of damage; minor repairs might cost $50-$100 while extensive rewiring could run upwards of $300.
- Transmission Fluid Change: Generally costs between $100 and $200 depending on fluid type and labor costs.
Warnings and Recommendations
- Stop Driving Immediately: If you notice severe symptoms like slipping gears or harsh shifting, it’s crucial to stop driving your vehicle until repairs are made to avoid further damage to your transmission.
- Regular Maintenance: To prevent future issues related to transmission performance, ensure regular maintenance of your vehicle’s fluid levels and components.
- Professional Diagnosis Recommended: If you’re unsure about diagnosing or repairing issues related to P1739, consult with a professional mechanic who can provide accurate diagnostics and repairs.
Frequently Asked Questions About P1739
- What does error code P1739 mean?
P1739 indicates a problem in the 3rd clutch pressure switch circuit within an automatic transmission. - Can I drive my car with a P1739 code?
It’s not recommended as it can lead to further transmission damage; stopping driving immediately is advised. - How much does it cost to fix a P1739 code?
The cost can range from $50 for parts like switches up to several hundred dollars depending on necessary repairs. - What are common symptoms of P1739?
Symptoms include harsh shifting, slipping gears, delayed engagement, and illumination of the check engine light. - Is replacing the 3rd clutch pressure switch difficult?
It’s generally manageable for DIY mechanics; however, access may vary by vehicle model. - What else could cause a P1739 code?
Other causes include wiring issues, low transmission fluid levels, or problems with the PCM. - Can I reset my check engine light after fixing P1739?
Yes, after repairs are made you can reset it using an OBD-II scanner; if problems persist it will return. - Should I replace my transmission if I get a P1739 code?
No; often replacing just the pressure switch resolves issues without needing a new transmission.
In conclusion, understanding and addressing a P1739 trouble code promptly can save vehicle owners significant time and money while ensuring their vehicle operates smoothly. Regular maintenance practices combined with timely diagnostics will help keep your transmission functioning optimally.