The MFD28 has the ability to regulate the Haldex blocking level (VAG Gen1 PQ34 platform). Communication takes place via Can Bus, so no conversion of the original control unit on the rear axle is necessary.
The control is activated by a license.
The Haldex functionality is currently only intended for vehicles with a retrofitted Haldex or with a freely programmable control unit. For more details please get in touch with us.

– Video –
Our 4motion control in use on the quarter mile in a Golf 2 16V Turbo.
Customer use in mountain racing
– Functionality –




You can also store a new widget type in the display, which shows the current status and locking level of the 4motion drive.
There are currently two widget types to choose from: LOCK and RACE
- The Haldex is permanently locked and can only be opened (IDLE) and locked (LOCK) by pressing your finger on the widget.
- The 4motion control blocks via a freely selectable sensor and a limit (e.g. boost pressure >-0.3bar)
- a second sensor (e.g. speed >250 km/h) opens the rear axle again
- Both sensors and limits are freely selectable and adjustable.
- The widget can also be opened (IDLE) and reactivated (RACE) at any time by pressing a finger on the widget.
If the locking level is only 56% , either the motor is not running (no speed detected) or the brake is applied.
Colors
In certain situations, the widget changes color to the following colors:
GREEN | Haldex exists in the Can Bus – the current blocking level and the desired blocking level match |
YELLOW | Haldex exists in the Can Bus – it is open (0% blocking level), no power is transmitted |
ORANGE | Haldex exists in the Can Bus – Haldex lock level and desired lock level do not match |
RED | Error condition |
Error conditions
If the widget turns
RED , the error code is displayed at the same time.
ERROR1 | the Haldex is in an error state |
ERROR2 | Overtemperature of the Haldex |
ERROR3 | The Haldex is in emergency mode |
ERROR4 | Haldex warning lamp active |
ERROR5 | No Haldex connected to the Can Bus |
Our Haldex control has already been tested in a wide variety of areas:
- 1/4 mile
- 1/2 mile
- circuit
- hill climb
- Drift training
We present one of the test vehicles in more detail here: Testing the Haldex control system
– Connection –
The display, control unit and 4motion control unit together form a CAN bus. The display and control unit have the CAN bus termination active (120 ohm resistance). In addition, the handbrake switch and brake light must be connected. If one of the two is active, the clutch opens. The power supply must also be connected.
