OpenHaldex-S3

OpenHaldex-S3 mobile interface and install screenshots

Free public-source DIY firmware
DIY Haldex AWD control for compatible VW and Audi vehicles.

OpenHaldex-S3 is a free public-source Haldex AWD controller built for the LilyGo T-2CAN ESP32-S3 board. It supports Gen 1, 2, 4, and 5 Haldex systems and introduces original software features to the community, including map-based control, web-based setup, live diagnostics, CAN View, and simple no-solder self-installation.

No soldering or advanced electrical knowledge required.

Engineered to Factory Standards, Built for the Community.

WHAT YOU NEED

INSTALL OPENHALDEX-S3

CHECK COMPATIBILITY

OpenHaldex-S3 isn’t a hobby prototype. It is coded and real-road tested by a dual-certified VW/Audi Electrical, Network, and High-Voltage Diagnostic Specialist using OEM ODIS instrumentation and raw CAN-bus validation.

Easy to build and install in minutes.

Supports Gen 1, 2, 4, and 5 VW and Audi Haldex systems.

If you can wire a light switch, you can build this.

Lift the rear seat, plug it in, and you’re done.

No soldering required. No factory wire cutting. No permanent modifications.
OpenHaldex-S3 uses a simple inline adapter made from OEM-style Haldex connectors and LilyGo T-2CAN screw terminals.

What OpenHaldex-S3 Does

  • Direct control over Haldex AWD behavior
  • Mode switching with ESP button (or any button you choose)
  • Speed, throttle, RPM, and map-based locking
  • Gen 5 support with decoded MQB CAN signals
  • One-click calibrate to your Haldex for accurate AWD control
  • Web-based control panel and online firmware updates

OpenHaldex-S3 is the original, verifiable public source of many advanced software features later found in Forbes Automotive OpenHaldex-C6 v2.10+.
These include the HTML/JS web interface, map editor, live tuning tools, CAN View, SavvyCAN-oriented tooling, OTA workflow, error logging, PlatformIO development structure, web-based API control UDS/KWP/TP2.0 native support, and more.
Check the public code history here: https://github.com/meatro/OpenHaldex-S3#public-history

Build OpenHaldex-S3 for Under $50

What You Need

  • LilyGo T-2CAN ESP32-S3 board (~$30)
  • OEM VW/Audi Haldex connectors (~$15)
    Gen 1: 1J0-973-714 and 1J0-973-814
    Gen 2-5: 1J0-973-713 and 1J0-973-813
  • Small enclosure (~$10)
  • Small screwdriver
LilyGo T-2CAN ESP32-S3 board used for OpenHaldex-S3
OpenHaldex-S3 hardware and OEM Haldex connectors

Build

To run OpenHaldex-S3, only 6 connections are required:

  1. 12V+ power (12-24V input)
  2. Ground (GND)
  3. Haldex CAN High (CANHA)
  4. Haldex CAN Low (CANLA)
  5. Vehicle CAN High (CANHB)
  6. Vehicle CAN Low (CANLB)

Note: CAN High is Orange/Black and CAN Low is Orange/Brown.
Brake, park brake, and other unused OEM wires should be connected directly together to preserve the original circuit path.

Flash

  1. Connect USB to the LilyGo T-2CAN
  2. Enter boot mode
    Hold BOOT, press and release RESET, then release BOOT
  3. Click Install below for your desired OpenHaldex firmware variant

Install OpenHaldex-S3

OpenHaldex-S3

OpenHaldex-S3 is our custom OpenHaldex build for the LilyGo T-2CAN, created for users who want a more advanced and configurable DIY Haldex controller.

It includes map-based control, advanced settings, live diagnostics, and a web-based setup interface.

v1.1

OpenHaldex-S3 screenshots and mobile interface

OpenHaldex-S3 Setup

  1. Use your phone, tablet, or laptop
  2. Connect to the available OpenHaldex-S3 hotspot
  3. Browse to 192.168.4.1
  4. Configure your setup page
  5. Customize your AWD behavior

The Truth About “Open Source” Haldex Controllers

Update: OpenHaldex-C6 source and MIT licensing have been restored. OpenHaldex-S3 is now also distributed under one permissive MIT license across firmware, web UI, bundled data assets, release metadata, and documentation. The history below remains as provenance for feature origins and source continuity.

While other commercial OpenHaldex such as OpenHaldex-C6 variant from Forbes Automotive are marketed on social media and web storefronts claim to be “fully open-source,” their underlying code for advanced performance features is completely closed, distributing binary-only blobs under a restrictive Source-Available License (FASL v1.0). OpenHaldex-S3 is the true home of transparent OpenHaldex innovation.

Compatible Haldex Generations and Vehicles

OpenHaldex-S3 supports compatible Gen 1, 2, 4, and 5 Haldex applications across selected VW and Audi vehicles.

  • Audi A3 / S3 8L Quattro 1998-2003
  • Audi TT 8N Quattro 1998-2006
  • VW Bora 2.8 V6 4Motion 1998-2004
  • VW Golf 1J Mk4 R32 4Motion 1998-2004
  • VW Sharan 7M Phase 1 Mk1 1998-2007
  • VW New Beetle RSi 1998-2003
  • Skoda Octavia 1U 4×4 Mk1 1998-2004
  • Seat Leon 1M Mk1 Cupra4 1998-2005
  • Seat Alhambra 7M 1998-2007

  • Audi A3 / S3 8P Quattro pre-facelift 2004-2008
  • Audi TT / TTS 8J Quattro pre-facelift 2007-2009
  • Volkswagen Golf 1K Mk5, R32, 4Motion 2004-2008
  • Volkswagen Passat 3C, 4Motion, Santana, CC 2005-2009
  • Volkswagen Transporter T5 pre-facelift 2003-2009
  • Seat Altea 2007-2010
  • Seat Alhambra 7M facelift 2005-2010
  • Skoda Octavia 1Z pre-facelift 2004-2009

  • VW Golf Mk6 5K 4Motion 2008-2012
  • VW Golf R Mk6 5K 2008-2012
  • VW Tiguan 2008-2014
  • VW Sharan 7N Mk2 2011-2015
  • VW Passat, CC, B7 2010-2015
  • VW Transporter late-model T5 facelift 2009-2015
  • VW Caddy Mk3 2K facelift 2010-2015
  • Audi A3 / S3 8P facelift 2009-2012
  • Audi TT / TTS / TTRS 8J facelift 2008-2012
  • Audi Q3 / RS Q3 2011-2013
  • Seat Altea XL / Freetrack 2010-2015
  • Seat Alhambra 7N 2011-2013
  • Skoda Yeti pre-facelift 2009-2014
  • Skoda Superb 3T 2008-2014
  • Skoda Octavia 4×4 / Scout / vRS 4×4 1Z facelift 2009-2014

  • VW Golf Mk7 and Mk7.5 R / 4Motion
  • VW Passat B8 / Arteon 4Motion
  • VW Atlas / Teramont 4Motion
  • VW Tiguan
  • VW Sportwagen / Alltrack Golf
  • Audi S3 8V Quattro
  • Audi TT / TTS / TTRS 8S Quattro
  • Audi Q3 F3 Quattro
  • Skoda Octavia 5E 4×4 / Scout
  • Skoda Superb 3V 4×4
  • Skoda Kodiaq 4×4
  • Seat Leon 5F 4Drive / Cupra
  • Seat Ateca 4Drive

  • What is OpenHaldex-S3?
    OpenHaldex-S3 is a free DIY Haldex AWD controller for compatible VW and Audi vehicles. It runs on the LilyGo T-2CAN ESP32-S3 board and supports Gen 1, 2, 4, and 5 Haldex systems.
  • How does OpenHaldex-S3 compare to OpenHaldex-C6 software?
    Public GitHub history shows OpenHaldex-S3 source was imported into the Forbes Automotive OpenHaldex-C6 repository shortly after the original S3 snapshot, including firmware source, web UI files, maps, CAN View code, PlatformIO configuration, and release metadata. OpenHaldex-S3 is the original, verifiable public source of many advanced software features later found in OpenHaldex-C6 v2.00+, including speed/throttle tuning and interpolation, DBC-driven CAN View, GVRET/SavvyCAN-oriented tooling, modern HTML/JS web interface, API-driven control, OTA workflow, and more.
  • Does OpenHaldex-S3 require soldering?
    No. OpenHaldex-S3 does not require soldering. The intended install uses the LilyGo T-2CAN screw terminals and OEM-style VW/Audi Haldex connectors. No factory wiring is cut or permanently modified. Crimping or repinning connector terminals may be needed depending on the connector parts used, but soldering is not required.
  • What vehicles are compatible with OpenHaldex-S3?
    OpenHaldex-S3 supports selected VW and Audi Haldex applications across Gen 1, 2, 4, and 5 systems. See the compatibility section above for common supported vehicles.
  • Is OpenHaldex-S3 safe to use?
    OpenHaldex-S3 has been real-road tested for thousands of miles without incident. It installs on the fused OEM Haldex circuit, supports normal vehicle operating voltage (12-24V), and does not modify general CAN traffic or override factory safety systems.
  • Does OpenHaldex-S3 cause warning lights?
    Under normal operation, no warning lights are expected. During aggressive driving, certain settings can trigger a temporary traction control warning. This clears after a key cycle.
  • Is the LilyGo T-2CAN ESP32-S3 suitable for automotive use?
    Yes, for this application. The T-2CAN is a dual-CAN ESP32-S3 board with a 12-24V input stage and has proven stable in real vehicle use as a DIY Haldex controller. Additionally, the dual-core CPU means that important CAN functions are performed independently of busywork, such as wifi, visualizations, etc.
  • Why should I try OpenHaldex-S3?
    Because it is free, easy to build, easy to remove, and built on inexpensive off-the-shelf hardware. It gives compatible VW and Audi owners a simple way to try map-based Haldex control without buying dedicated aftermarket hardware first.
  • What if I do not like OpenHaldex-S3?
    That is fine. It can be removed by unplugging it, and you still have a LilyGo T-2CAN development board.