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Tesla Model 3 or Y with HW3/HW4: openpilot quick start

Buy a comma four with the Tesla A (HW3) or B (HW4) harness, plug in behind the glovebox, install stock openpilot.

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comma four with its screen on

Who this is for

Tesla Model S, 3, X or Y owners with HW3 or HW4 who want openpilot without a special fork.

comma fourcomma 3X

You need

  • A comma four or comma 3X
  • Tesla A harness for HW3 or Tesla B harness for HW4
  • Trim tools to reach the autopilot computer behind the glovebox

In plain words

Why this guide matters

Tesla Model 3 and Y owners with HW3 or HW4 can run openpilot with no special fork. This quick start from the harness designer tells you which comma harness to buy and where it plugs in. Follow it and you are driving on stock openpilot after one plug behind the glovebox.

The short version

What the full guide walks you through

  1. Check whether your car is HW3 or HW4.

  2. Order the matching harness with the device.

  3. Install the harness at the autopilot computer behind the glovebox.

  4. Install stock openpilot and drive.

  5. If you see Car Unrecognized, follow the car identification page.

Before you start

  • The A-pillar cable in the video is only for the optional add-on cable.
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The full written guide belongs to xnor wiki. Checked on September 10, 2026.

Quick answers

Questions people ask

Which harness does my Tesla need?

Tesla A for HW3 and Tesla B for HW4. Both are sold by comma and by xnor.shop.

Does a Model S or X work?

Yes; the page covers Model S, 3, X and Y with HW3 or HW4.

Do I need the A-pillar cable in the video?

No; that is only for the optional Vehicle CAN add-on. The standard harness plugs in behind the glovebox only.

Check your car

Cars this guide talks about

Support changes by year and trim. Open your exact car before you buy anything.

Tesla Model 3 (with HW3) 2019–2023Tesla Model 3 (with HW4) 2024–2025Tesla Model Y (with HW3) 2020–2023Tesla Model Y (with HW4) 2024–2025All Tesla models

Related

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Not sure this is your path?

Check your exact car first, then choose software and hardware.

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Photos: comma.ai. Guide content belongs to xnor wiki. CommaGuide is an independent guide and is not affiliated with comma.ai or xnor wiki.

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