The P1587 trouble code is a diagnostic trouble code (DTC) that indicates a malfunction in the throttle control system. Specifically, it signifies a “Throttle Control Unit Modulated Command Malfunction” or issues related to the communication between the Powertrain Control Module (PCM) and the Throttle Actuator Control Module (TACM). This code can lead to performance issues in vehicles, affecting acceleration and overall drivability. Understanding the causes, symptoms, and solutions for this code can help vehicle owners and DIY mechanics effectively diagnose and resolve the issue.
| P1587 Code Meaning | P1587 Code Common Causes |
|---|---|
| Throttle Control Unit Modulated Command Malfunction | Faulty wiring between PCM and TACM |
| PCM to TACM throttle command redundancy circuit failure | Defective throttle body assembly |
| High resistance in throttle control circuit | Faulty accelerator pedal position sensor |
| Communication error between modules | Corroded or damaged connectors |
| Low voltage signal from throttle position sensor | Software issues in PCM |
Symptoms of P1587 Code
When the P1587 code is triggered, vehicle owners may notice several symptoms, including:
- Check Engine Light: The most common indicator is the illumination of the check engine light on the dashboard.
- Reduced Engine Performance: The vehicle may experience reduced power or acceleration, making it difficult to drive normally.
- Unstable Idle: The engine might idle roughly or stall unexpectedly.
- Throttle Response Issues: There may be delays in throttle response or erratic behavior during acceleration.
- Difficulty Starting: Some vehicles may have trouble starting due to electrical issues related to the throttle control system.
Technical Explanations
The P1587 code is primarily associated with electronic throttle control systems. This system uses sensors and actuators to manage engine power and efficiency without traditional mechanical linkages. The PCM communicates with the TACM to ensure that throttle position matches driver input from the accelerator pedal.
Key Components Involved:
- Powertrain Control Module (PCM): The brain of the vehicle’s engine management system, responsible for processing data from various sensors.
- Throttle Actuator Control Module (TACM): This module receives commands from the PCM to adjust the throttle position based on driving conditions.
- Accelerator Pedal Position Sensor (APPS): This sensor detects how far the accelerator pedal is pressed and sends this information to the PCM.
Common Issues Leading to P1587:
- Wiring Problems: Damaged or corroded wires between the PCM and TACM can disrupt communication.
- Faulty Sensors: Malfunctions in sensors such as the APPS can lead to incorrect readings being sent to the PCM.
- Connector Issues: Loose or corroded connectors can cause intermittent signals that trigger fault codes.
- Software Glitches: Sometimes, outdated or corrupt software in the PCM can lead to erroneous codes being set.
Step-by-Step Diagnosis
Diagnosing a P1587 code requires a systematic approach:
- Scan for Codes: Use an OBD-II scanner to confirm that P1587 is present and check for any additional codes that may provide context.
- Visual Inspection:
- Inspect wiring harnesses connected to both the PCM and TACM for signs of damage or corrosion.
- Check connectors for looseness or corrosion.
- Test Voltage and Ground:
- Use a multimeter to check for proper voltage at the TACM connector.
- Ensure that ground connections are secure and free of corrosion.
- Sensor Testing:
- Test the APPS using a multimeter to ensure it operates within specified voltage ranges.
- Check the throttle position sensor for proper operation.
- Module Communication Check:
- Using a scan tool, check for communication between modules.
- If communication fails, further investigate wiring issues or module failures.
- Software Update:
- If all hardware checks out, consider updating or reprogramming the PCM software if applicable.
Solution Methods
Resolving a P1587 code typically involves one or more of the following actions:
- Repair Wiring Harness: If damaged wiring is found, repair or replace it as necessary.
- Replace Faulty Sensors: If testing reveals that sensors are malfunctioning, replace them with OEM parts.
- Clean Connectors: Use electrical contact cleaner on corroded connectors to ensure good electrical contact.
- Reprogram/Update PCM: If software issues are suspected, consult with a dealer or qualified technician for reprogramming options.
Cost Estimates
The cost of repairs related to P1587 can vary significantly based on several factors:
- Wiring Repairs: $100 – $300 depending on labor rates and extent of damage.
- Sensor Replacement: $50 – $200 per sensor depending on make and model.
- PCM Reprogramming: $100 – $500 depending on dealership fees or specialized services required.
Warnings and Recommendations
- Always disconnect the battery before working on electrical components to avoid shorts.
- If you are not comfortable diagnosing electrical issues, seek professional help to avoid further complications.
- Regular maintenance checks can help prevent issues related to wiring and connectors due to wear over time.
Closing Paragraph
The P1587 trouble code highlights critical communication errors within your vehicle’s throttle control system. Understanding its implications allows vehicle owners and DIY mechanics to approach diagnostics methodically. By following systematic troubleshooting steps and addressing potential causes effectively, you can restore your vehicle’s performance while avoiding costly repairs down the line. Always consult your vehicle’s service manual for specific guidance tailored to your model when dealing with trouble codes like P1587.
Frequently Asked Questions About P1587
- What does P1587 mean?
P1587 indicates a malfunction in the throttle control system, specifically relating to communication between the PCM and TACM. - How serious is a P1587 code?
A P1587 code can lead to reduced engine performance and drivability issues; it’s advisable to address it promptly. - Can I drive my car with a P1587 code?
While it may be possible, driving with this code can lead to unsafe conditions due to potential power loss. - What should I do if I get a P1587 code?
Start by diagnosing using an OBD-II scanner, then inspect wiring and sensors before attempting repairs. - Is it safe to clear a P1587 code?
You can clear it after repairs; however, if it reappears, further diagnosis is needed. - How much does it cost to fix a P1587 code?
The cost varies widely but typically ranges from $100 for minor fixes up to $500 for more extensive repairs. - Can I fix a P1587 code myself?
If you have basic mechanical skills and tools, you may be able to diagnose and fix minor issues; otherwise, professional help is recommended. - What vehicles commonly experience P1587 codes?
This code can occur in various makes and models but is particularly noted in certain Jaguar models.