Webasto Thermo Top C

Hi, I have a Webasto Thermo Top C, manufactured in 2004. Now I have the problem that it no longer starts. Two weeks ago it was running perfectly, and suddenly it only starts the burner fan and the circulation pump when switched on. I have cleaned the combustion chamber and tested the dosing pump. Everything seems to be okay. I wanted to have the error memory read out at a workshop, but the technician said that it is impossible to read it out because the control unit is not responding. I would be grateful if someone could help me. (maybe Flammwächter/Glühstift ?)

hello,

also had the same problems with my TT-C (diesel). however, I was able to read the error codes. and this also confirmed the suspicion of a glow plug issue.
After that, I wanted to arrange the purchase of the glow plug myself from a Webasto dealer; however, they only wanted to sell the entire combustion chamber. Afterwards, I bought the glow plug from a VW dealer (since VW buses also have the TT installed).

greetings.

Thank you for the super quick response. I think I'll try to get a glow stick. If that's the case, I will report it here.
I really don't hope for a faulty control unit.

I haven't been successful with the multimeter , but I have now found the fault. There is a loose connection on the control unit. When I remove the screws of the control unit cover, everything works as it should, but as soon as I tighten the cover, the heater stops. A little tinkering, a little adjustment (capacitors), and now it's even running again with the lid securely fastened.
Finally, it's warm again.