The P1739 trouble code is a diagnostic trouble code (DTC) that indicates a problem in the third clutch pressure switch circuit of an automatic transmission. This code is primarily associated with vehicles equipped with electronically controlled automatic transmissions. When the powertrain control module (PCM) detects that the readings from the third clutch pressure switch are outside of the expected range, it triggers the P1739 code. This can lead to issues such as rough shifting, slipping, or even transmission failure if not addressed promptly.
| P1739 Code Meaning | P1739 Code Common Causes |
|---|---|
| Faulty third clutch pressure switch | Wiring issues in the pressure switch circuit |
| Short circuit in the clutch pressure switch circuit | Faulty PCM (Powertrain Control Module) |
| Open circuit in the clutch pressure switch circuit | Contaminated transmission fluid |
| Incorrect voltage readings from the switch | Mechanical failure within the transmission |
Symptoms of P1739 Code
When dealing with a P1739 code, vehicle owners may notice several symptoms, including:
- Rough or hard shifting: The vehicle may shift abruptly between gears.
- Slipping transmission: The transmission may unexpectedly slip out of gear.
- Check Engine Light: The illumination of the check engine light on the dashboard.
- Poor acceleration: The vehicle may struggle to accelerate smoothly.
- Increased RPMs: Higher than normal RPMs without corresponding acceleration.
Technical Explanation
The P1739 code is specifically related to the third clutch pressure switch, which plays a crucial role in regulating hydraulic pressure within the transmission. This switch sends signals to the PCM regarding the hydraulic pressure applied to the third gear clutch. If there is an issue with this switch or its circuit, it can lead to improper shifting and other transmission-related problems.
How the Third Clutch Pressure Switch Works
- Signal Generation: The pressure switch generates a signal based on hydraulic pressure levels.
- Transmission Control: The PCM uses this signal to adjust shifting patterns and ensure smooth operation.
- Feedback Loop: If the signal is outside of expected parameters, it triggers a fault code (P1739) and may alter shifting behavior to protect the transmission.
Step-by-Step Diagnosis
Diagnosing a P1739 code involves several steps:
- Scan for Codes: Use an OBD-II scanner to confirm that P1739 is present and check for any additional codes that may provide context.
- Visual Inspection:
- Inspect wiring and connectors associated with the third clutch pressure switch for signs of damage or corrosion.
- Check for any fluid leaks around the transmission area.
- Test Voltage at Switch:
- Disconnect the connector from the third clutch pressure switch.
- With the ignition on (engine off), use a multimeter to check for voltage at the connector. You should see approximately 12 volts.
- Resistance Testing:
- Measure resistance across the terminals of the third clutch pressure switch while disconnected. A reading significantly lower than expected indicates a faulty switch.
- Live Data Monitoring:
- Use a scan tool capable of live data monitoring to observe real-time readings from the third clutch pressure switch while driving. Look for erratic or unexpected values.
Solution Methods
Once diagnosed, several solutions can be applied depending on what was discovered during troubleshooting:
1. Replace Faulty Third Clutch Pressure Switch
If testing confirms that the switch is faulty:
- Cost Estimate: Replacement parts typically range from $30 to $100, depending on make and model.
- Installation Time: Approximately 1 hour for most vehicles.
2. Repair Wiring Issues
If damaged wiring is found:
- Cost Estimate: Repair costs can vary widely based on labor rates and parts needed but expect around $50 to $200.
- Installation Time: 1-2 hours depending on severity and location of damage.
3. Replace PCM
If all else fails and PCM issues are suspected:
- Cost Estimate: A new PCM can range from $200 to $800 plus programming costs.
- Installation Time: 2-4 hours depending on vehicle complexity.
4. Fluid Change
If contaminated fluid is suspected:
- Cost Estimate: Transmission fluid change costs typically range from $100 to $300.
- Installation Time: About 1 hour for most vehicles.
Warnings and Recommendations
- Always disconnect battery power before working on electrical components to avoid shorts or shocks.
- If you are not confident in diagnosing or repairing transmission issues, it is highly recommended to seek professional assistance as improper handling can lead to further damage.
- Regular maintenance, including fluid changes and inspections, can help prevent issues like those indicated by a P1739 code.
Closing Paragraph
The P1739 trouble code signifies an important issue within your vehicle’s transmission system that should not be ignored. Understanding its meaning, symptoms, and repair methods empowers vehicle owners and DIY mechanics alike to address potential problems proactively. By following proper diagnostic steps and solutions outlined in this guide, you can ensure your vehicle remains safe and operational while preventing costly repairs down the line.
Frequently Asked Questions About P1739
- What does P1739 mean?
The P1739 code indicates a problem with the third clutch pressure switch circuit in an automatic transmission. - Can I drive my car with a P1739 code?
It is not advisable to drive with this code as it can lead to further transmission damage. - How much does it cost to fix a P1739 code?
The cost varies widely based on whether you need to replace a sensor, repair wiring, or replace the PCM, ranging from $30 to over $800. - What are common symptoms of a P1739 code?
Common symptoms include rough shifting, slipping transmission, check engine light illumination, and poor acceleration. - Is it safe to replace the third clutch pressure switch myself?
If you have basic mechanical skills and tools, replacing it can be done DIY; otherwise, consult a professional. - What tools do I need for diagnosing P1739?
A basic OBD-II scanner, multimeter for voltage/resistance testing, and standard hand tools will be required. - How often should I check my transmission fluid?
It’s recommended to check your transmission fluid every 30,000 miles or as specified by your vehicle’s manufacturer. - Can other codes appear alongside P1739?
Yes, other related codes may appear; it’s important to diagnose all codes together for accurate repairs.