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2021 Tacoma TRD Off-Road: Pre-Collision System Malfunction & False Alarms

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Chris P. · rep 0 · May 22, 2:21 AM · 1 replies · solved · Question

Vehicle: 2021 Toyota Tacoma TRD Off-Road

My 2021 Toyota Tacoma TRD Off-Road has been giving me headaches with its Toyota Safety Sense (TSS) Pre-Collision System (PCS). I frequently get a 'Pre-Collision System Malfunction' warning light on the dash, and sometimes it just says 'PCS Unavailable'.

Even worse, I've had a few false alarms where the system brakes hard for no apparent reason, or warns me of an impending collision when there's nothing in front of me. This happens even when the radar sensor in the grille is clean. It's making me nervous to rely on the system.

Is this a common problem with the TSS 2.0 system in 2020-2023 Tacomas or other Toyota trucks? What could be causing these malfunctions and false positives? I'm concerned about the reliability of this safety feature.

✓ Accepted solution

ClearTheCode Admin

ClearTheCode Team · rep 0 · May 22, 2:21 AM

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ClearTheCode admin answer:

Issues with the Toyota Safety Sense (TSS) Pre-Collision System (PCS), including malfunction warnings and false alarms, have been reported by some owners, particularly with the earlier iterations of TSS 2.0 in models like your 2021 Tacoma. While designed for safety, these glitches can be concerning.

  1. Common Causes:

    • Sensor Obstruction/Contamination: Even if the visible radar sensor in the grille appears clean, minor debris, ice, or even heavy rain/snow can temporarily obstruct it. However, persistent issues suggest something more.
    • Sensor Misalignment: The radar sensor (located behind the Toyota emblem in the grille) or the camera (mounted at the top of the windshield) can become slightly misaligned due to minor impacts, vibrations, or even improper installation during a windshield replacement. This is a very common cause of false alarms or system unavailability.
    • Software Glitches: As with any complex electronic system, software bugs can lead to erroneous readings or system malfunctions. Toyota often releases software updates to refine TSS performance.
    • Electrical Issues: Less common, but wiring issues or a faulty sensor/camera unit could also be the culprit.

  2. OBD Codes: A diagnostic scan will likely reveal specific codes related to the PCS, such as:

    • C1A00: Front Radar Sensor Malfunction
    • C1A01: Front Radar Sensor Communication Error
    • C1A02: Front Radar Sensor Beam Axis Adjustment Incomplete
    • C1A03: Front Camera Malfunction

  3. When to See a Shop: Given that this is a critical safety system, you should take your Tacoma to a Toyota dealership immediately. Do not attempt to diagnose or repair these systems yourself, as improper calibration can lead to dangerous situations.

  4. What the Shop Will Do:

    • Diagnostic Scan: They will use specialized Toyota diagnostic tools to read all stored codes from the PCS module.
    • Sensor Calibration: The most common fix for these issues is recalibrating the front radar sensor and/or the windshield-mounted camera. This requires specific tools and a controlled environment.
    • Software Update: They will check for and apply any available software updates for the TSS system.
    • Physical Inspection: Technicians will inspect the radar sensor, camera, and associated wiring for any physical damage or loose connections.
    • Test Drive: A thorough test drive will be conducted to confirm the fix and ensure the system operates correctly.

It's important to get this resolved quickly to ensure your safety features are functioning as intended.

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