Toyota Pre-Collision System Not Working? Here’s What You Need to Know

Is Your Toyota’s Pre-Collision System Acting Up? A Comprehensive Troubleshooting Guide

The Toyota Pre-Collision System (PCS) is an advanced safety feature designed to help prevent or mitigate frontal collisions. It is part of the Toyota Safety Sense (TSS) suite of driver assistance technologies. The PCS uses a combination of cameras and radar sensors to detect vehicles, pedestrians, and in some cases, cyclists ahead of the vehicle. Key components of the Toyota PCS include:

  • Front-facing camera (typically mounted behind the rearview mirror)
  • Millimeter-wave radar sensor (usually located behind the Toyota emblem on the front grille)
  • Electronic control unit (ECU) to process sensor data
  • Visual and audible warning systems
  • Automatic emergency braking capability

How the Pre-Collision System Works

The Toyota PCS operates through the following steps:

  1. Constant monitoring: The system continuously scans the road ahead using its camera and radar sensors.
  2. Object detection: When a potential collision risk is detected (e.g. a vehicle or pedestrian), the system analyzes the object’s size, speed, and trajectory.
  3. Risk assessment: The PCS calculates the likelihood of a collision based on the vehicle’s speed and distance to the object.
  4. Driver alert: If a high collision risk is determined, the system provides visual and audible warnings to the driver.
  5. Brake assistance: If the driver begins to brake, the system may increase braking force to help avoid the collision.
  6. Automatic emergency braking: If the driver does not take action and a collision is imminent, the PCS can automatically apply the brakes to reduce impact speed or potentially avoid the collision entirely.

Common PCS Malfunction Symptoms

When the Toyota Pre-Collision System experiences a malfunction, you may notice one or more of the following symptoms:

  1. Warning lights: The PCS warning light (typically an icon of a car with exclamation marks) illuminates on the dashboard.
  2. Error messages: The multi-information display may show messages like “Pre-Collision System Malfunction” or “Visit Your Dealer”.
  3. System deactivation: The PCS may automatically turn off when a malfunction is detected.
  4. Inconsistent operation: The system may activate unexpectedly or fail to activate when it should.
  5. Other safety system warnings: Since the PCS is integrated with other TSS features, you may also see warnings for systems like Lane Departure Alert or Dynamic Radar Cruise Control.

Causes of PCS Malfunctions

Several factors can contribute to a Toyota Pre-Collision System malfunction:

  1. Sensor obstructions: Dirt, snow, ice, or debris covering the front camera or radar sensor.
  2. Misaligned sensors: Physical impacts or improper repairs can knock sensors out of alignment.
  3. Electrical issues: Wiring problems, blown fuses, or battery issues can affect PCS operation.
  4. Software glitches: Outdated or corrupted software in the PCS control module.
  5. Hardware failures: Malfunctioning cameras, radar units, or control modules.
  6. Environmental factors: Extreme temperatures, heavy rain, or bright sunlight can temporarily affect sensor performance.
  7. Aftermarket modifications: Some non-OEM accessories or modifications may interfere with PCS operation.

How to Reset the Pre-Collision System

In many cases, a simple reset procedure can resolve minor PCS malfunctions. Here’s a step-by-step guide to resetting the Toyota Pre-Collision System:

  1. Turn off the vehicle: Completely shut down the engine and electrical systems.
  2. Wait for 5 minutes: This allows the vehicle’s computer systems to fully reset.
  3. Clean sensors: While waiting, check and clean the front camera (near the rearview mirror) and radar sensor (behind the Toyota emblem) using a soft, lint-free cloth.
  4. Restart the vehicle: Turn the ignition on or press the start button.
  5. Check warning lights: Observe if the PCS warning light turns off after the system performs its self-check.
  6. Test drive: Take a short drive to see if the system functions normally and if any warning messages have cleared.
  7. Re-enable the system: If the PCS was previously turned off, re-enable it through the vehicle settings menu in the multi-information display.

If the malfunction persists after this reset procedure, further diagnostics may be necessary.

Advanced Troubleshooting Steps

For more persistent PCS issues, try these additional troubleshooting steps:

  1. Battery check: Ensure the vehicle’s battery is in good condition and fully charged, as low voltage can cause system malfunctions.
  2. Fuse inspection: Check the fuses related to the PCS and replace any that are blown.
  3. Software updates: Inquire with your Toyota dealer about any available software updates for the PCS system.
  4. Sensor alignment: If you suspect misaligned sensors (e.g., after a minor collision), have a professional check and recalibrate them.
  5. Diagnostic scan: Use an OBD-II scanner to check for specific error codes related to the PCS malfunction.
  6. Wiring inspection: Look for any visible damage to wiring harnesses, particularly near the front of the vehicle.
  7. Test in different conditions: Sometimes, environmental factors can cause temporary malfunctions. Test the system under various weather and lighting conditions.

When to Seek Professional Help

While many PCS issues can be resolved through simple resets or basic troubleshooting, there are situations where professional assistance is necessary:

    1. Persistent warnings: If error messages or warning lights remain after multiple reset attempts.
    2. Physical damage: Any visible damage to sensors, cameras, or surrounding areas.
    3. Recent collisions: Even minor accidents can affect sensor alignment and system performance.
    4. Inconsistent behavior: If the system works intermittently or behaves erratically.
  1. Multiple system failures: When other Toyota Safety Sense features are also malfunctioning.
  2. Post-repair issues: If problems occur after recent vehicle repairs or maintenance.
  3. Warranty concerns: For vehicles under warranty, having issues documented by a dealer can be important for potential claims.

Importance of Professional Diagnostics

Toyota dealerships and certified mechanics have specialized diagnostic tools and training to accurately identify and resolve PCS issues. Professional diagnostics typically involve:

  1. Advanced scanning: Using Toyota-specific diagnostic equipment to read detailed error codes.
  2. Software analysis: Checking for software conflicts or outdated firmware.
  3. Comprehensive sensor testing: Evaluating the performance of cameras and radar units.
  4. Calibration procedures: Precisely aligning and calibrating sensors if necessary.
  5. Road testing: Verifying system functionality under various driving conditions.
  6. Factory updates: Applying any relevant Toyota technical service bulletins or recalls.

Preventing Future PCS Malfunctions

To minimize the risk of future Pre-Collision System issues:

  1. Regular cleaning: Keep the front camera and radar sensor areas clean and free of obstructions.
  2. Avoid modifications: Be cautious with aftermarket accessories that could interfere with sensors.
  3. Prompt repairs: Address any collision damage, even minor bumper impacts, promptly.
  4. Software updates: Stay current with any Toyota-recommended software updates for your vehicle.
  5. Regular maintenance: Follow the prescribed maintenance schedule in your owner’s manual.
  6. Proper jump-starting: If jump-starting your vehicle, ensure it’s done correctly to avoid electrical system damage.
  7. Quality replacements: When replacing windshields or bumpers, use Toyota-approved parts to maintain proper sensor function.

Understanding PCS Limitations

While the Toyota Pre-Collision System is a valuable safety feature, it’s important to understand its limitations:

  1. Weather sensitivity: Heavy rain, fog, or snow can reduce system effectiveness.
  2. Lighting conditions: Very bright sunlight or low-light situations may affect camera performance.
  3. Small objects: The system may not detect very small obstacles or animals.
  4. Sudden movements: Objects that suddenly enter the vehicle’s path may not be detected in time.
  5. High speeds: The system’s effectiveness decreases at very high speeds.
  6. Steep roads: Hills and sharp curves can affect sensor coverage areas.
  7. Towing: Towing a trailer may interfere with radar sensor functionality.

Understanding these limitations helps drivers maintain realistic expectations and not over-rely on the system.

The Future of Toyota’s Pre-Collision System

Toyota continues to evolve and improve its Pre-Collision System technology. Future developments may include:

  1. Enhanced detection: Improved ability to recognize a wider range of objects and scenarios.
  2. Expanded operational range: Functioning effectively at higher speeds and in more diverse conditions.
  3. Integration with V2X: Vehicle-to-everything communication to enhance predictive capabilities.
  4. AI and machine learning: More sophisticated algorithms to better predict potential collision scenarios.
  5. Sensor fusion: Combining data from multiple types of sensors for more accurate detection.
  6. Expanded collision mitigation: Potentially including side and rear collision prevention features.
  7. User customization: More options for drivers to adjust system sensitivity and behavior.

Toyota Pre-Collision System (PCS) Diagnostic Trouble Codes

The Toyota Pre-Collision System uses radar and cameras to detect potential collisions and can automatically apply the brakes if needed. If the system malfunctions, it will trigger a “Pre-Collision System Malfunction” warning message along with one or more diagnostic trouble codes (DTCs). Here are the common DTCs for the Toyota PCS, along with their descriptions, causes, and solutions:

C1A11: Pre-Collision System Malfunction

  • Description: General malfunction in the Pre-Collision System.
  • Causes: Faulty radar sensor, damaged wiring or connectors, software issues.
  • Solutions: Inspect and clean the radar sensor, check wiring for damage, update PCS software if available

U0137: Lost Communication With Pre-Collision System

  • Description: Communication error between the PCS module and other vehicle systems.
  • Causes: Damaged wiring, faulty PCS module, issues with other modules (e.g. ABS, ECM).
  • Solutions: Check wiring and connectors, test the PCS module, diagnose other vehicle systems for faults

B1650: Camera Malfunction

  • Description: Fault detected in the PCS camera system.
  • Causes: Dirty or obstructed camera lens, faulty camera, misalignment.
  • Solutions: Clean the camera lens, inspect for damage, realign or replace the camera if needed

B1214: Yaw Rate Sensor Malfunction

  • Description: Issue with the yaw rate sensor, which detects vehicle rotation.
  • Causes: Faulty yaw rate sensor, damaged wiring, calibration issues.
  • Solutions: Replace the yaw rate sensor, repair wiring, perform yaw rate sensor calibration.

C1A12: Radar Sensor Malfunction

  • Description: Fault in the millimeter wave radar sensor used by PCS.
  • Causes: Dirty or obstructed sensor, faulty sensor, incorrect aiming.
  • Solutions: Clean the radar sensor, check for damage, realign or replace the sensor.

U0100: Lost Communication With ECM/PCM

  • Description: PCS module cannot communicate with the engine control module.
  • Causes: Damaged wiring, faulty PCS or engine control module.
  • Solutions: Inspect wiring and connectors, test the PCS and ECM modules for proper operation.

In addition to these specific codes, some other factors can cause the Pre-Collision System to malfunction:

  • Aftermarket accessories interfering with the radar sensor (e.g. brush guards, winches)
  • Incorrect tire size throwing off vehicle speed calculations
  • Issues with the brake system, as PCS can apply the brakes automatically

If your Toyota is displaying a “Pre-Collision System Malfunction” warning, use an OBD-II scanner to check for diagnostic trouble codes. This will help narrow down the potential causes. Some issues, like a dirty radar sensor or camera lens, can be fixed easily. However, problems with faulty components or damaged wiring may require a visit to the dealer or a qualified mechanic to diagnose and repair.

Conclusion

The Toyota Pre-Collision System is a sophisticated safety feature designed to help prevent accidents and protect vehicle occupants. While it can experience malfunctions, many issues can be resolved through simple reset procedures or basic troubleshooting. Understanding how the system works, recognizing malfunction symptoms, and knowing when to seek professional help are key to maintaining this crucial safety feature. Regular maintenance, careful driving, and staying informed about your vehicle’s systems will help ensure that your Toyota Pre-Collision System continues to function effectively, providing an additional layer of safety on the road. Remember, while advanced safety technologies like PCS are valuable tools, they are not substitutes for attentive and responsible driving. By following the guidelines outlined in this comprehensive guide, Toyota owners can effectively manage PCS malfunctions, ensure optimal system performance, and contribute to safer roads for everyone.