OpenHaldex SS v1.1

Build your OpenHaldex controller

The board is a little computer that runs SS. The harness is a short set of wires and matching plugs that connects it between the car and the rear Haldex unit. Once it is set up, your phone browser becomes the control panel.

First, check your car. SS supports conventional VW Group Haldex Gen 1, 2, 4 and 5 systems. The Mk8 Golf R and 8Y RS3 use a different rear torque-splitter system and are not currently supported.

1. Gather the parts

• Board: LILYGO T-2CAN ESP32-S3 N16R8.
• Prewired connector pair for your Haldex generation: Gen 1 uses 1J0-973-714 and 1J0-973-814; Gen 2, 4 and 5 use 1J0-973-713 and 1J0-973-813.
• Small screwdriver for the board screw terminals.
• USB data cable and a computer with Chrome or Edge. A charge-only cable will not work for installation.
• Enclosure to protect the board, plus a way to secure the controller and wires.

Prewired plugs save you from crimping the connector terminals yourself. Check the official build guide before buying parts, and keep it open while building.

2. Make the six board connections

Four connections carry car data, called CAN. The other two power the board:

• Haldex side → CAN A: CAN High to CANHA, CAN Low to CANLA.
• Car side → CAN B: CAN High to CANHB, CAN Low to CANLB.
• Power and ground: use the correct power source and ground connection shown for your Haldex generation.

The official wiring guide shows the exact connector holes and the other wires that must continue straight through the harness. Match the numbered holes in the plugs, not wire colors alone. Check every connection before powering it.

3. Put SS on the board

1. Connect the board to your computer with the USB data cable.
2. Open the official SS installer in Chrome or Edge.
3. Click Install and select the board serial port when the browser asks.
4. Leave the cable connected until installation finishes and the board restarts.

Then follow the official guide to plug the checked harness into the car with the ignition off. Secure the board and wires. Continue to first startup to connect your phone and choose the first settings.

Already running S3, or updating SS?

Moving from S3: export maps and profiles you want to keep before installing SS. You need one USB installation so SS can set up its own storage. Old settings may need to be recreated in SS.

Updating SS: v1.1 lets you back up and restore your configuration. Later SS updates can run from Settings when the board also has an internet connection. The update replaces the software and dashboard while keeping saved settings and files. Park with the engine off and stop diagnostics, replay and logging first. Use USB to recover an interrupted update.

Read the official update instructions and SS software terms. The firmware is free for personal, non-commercial experimental or off-road use. See SS or S3? for the licensing differences.