Golf 4 TDI: Transmission Control Module Not Found

Hello fellow DIY enthusiasts,

I'm having a problem where my VCDS software can't find the transmission control unit because of too many error connections. However, it can find the engine control unit and everything else without any issues.

The real problem with the 116hp 4-cylinder TDI engine is that if you, for example, brake suddenly at 30 km/h and then want to reverse, it will engage reverse and start moving, but even if you press the accelerator pedal all the way down, the engine speed will remain at idle.

It briefly moved forward and then went into reverse, and the accelerator pedal started working again. After that, I tried to reproduce the error, but I wasn't able to.

But what's even more important to me is being able to read the error codes from the transmission control unit, but only if it's not found.

Hi,

Please provide the bit rates that the VCDS uses when establishing a connection via K-Line (Golf4 = all models) to other control units in your car.
It's located in the upper left corner, near the rotating indicator in the control unit information display, during the connection process, for example, "9613" or something similar.

Is your brake pedal switch working correctly? The switch position bits can be read using the diagnostic blocks of the engine control unit.

Best regards, Rainer.

Hello Rainer,

The catch is that I haven't actually bought the car yet. I only took it for a test drive yesterday, and that's when I noticed the problem with it not engaging in reverse and not accelerating. And when I tried to read the diagnostic codes, the control unit couldn't be found.

It's not likely due to the VCDS, as I have the same transmission in my Bora, and I can definitely read the data from it there.

Just occurred to me that the Golf has a non-original radio installed. I don't know who installed it, but if the radio is connected to the Gala connector with +12V and an antenna remote, I wonder how that might affect any of the control units.

Unfortunately, I didn't observe the bitrate at that moment, and it won't be possible to read it again without purchasing it.

It doesn't matter anymore because the car doesn't have a particulate filter (PF) and also doesn't have a green environmental sticker. I couldn't see it yesterday because the windshield was covered in ice.

Thank you for your help.