Passat 35i ECU: Can it work on a Golf 3?

Hello everyone,

I'm currently in the process of converting my T4 to a 1.9 TDI 1Z engine. The engine is from a Golf 3.
Okay, I'm having a problem with the engine control unit (ECU). My ECU from the Golf 3 has an immobilizer, but I can't use it. It's possible to have the immobilizer removed from the ECU, which costs around 100 euros. However, I know someone who would be willing to swap my ECU with his from a Passat 35i facelift model that doesn't have an immobilizer. Is that possible? My engine is from 1994, and the Passat is also from 1994.

It would be great if I could save that 100 euros.
Oh yeah, before anyone starts complaining about the WFS: My T4 is a 1994 model and also doesn't have WFS, so it should be fine .

Edit: I now also have the part numbers:
Passat: 028 906 021 B
Golf: 028 906 021 AF


Thank you and best regards,
Philipp.

Hi,

According to some forums, the 021B control unit was installed in Switzerland/Austria and does not have WFS (Wireless Functionality System). It should work with any 1Z model. It may be necessary to adapt the connector (only the coding in the corners, not electrically).
After that, check the error memory. An external height sensor might be necessary, as the one in the AF unit is internal.

Otherwise, I would simply take the key reader coil and the WFS control unit from a scrapped vehicle (or from this auction house, which would then need to be programmed) and mount them somewhere in the engine compartment (protected from heat and water splashes, of course). Then, I would connect them to the wiring harness and use the transponder from the original Golf key. For example, I would glue the transponder to the key reader coil using a two-component adhesive (a high-quality one, because if the transponder comes off, it's game over). Then, everything should be fine for the MST, and you can start the T4 with a push button.

Hello,
Stefan.

Hi,
The part number 028 906 021 B should only be used with the Passat model that has the 1Z chassis code. Therefore, you need to obtain the pin assignments for both the Golf and Passat Message Control Units (MSG) and adjust them accordingly.
Best regards,
Herbert.