Electric problem with Audi 80 Turbo

Hello friends I am new here and I think this page is magnificent for those who dedicate ourselves to repair some cars on our own.
I would be very grateful to those who could help me with a problem in an Audi 80 Turbo, because the rear mist preheating of diesel spark plugs; The fuses are fine and the truth is why to continue.
Without more thank you very much and in good time everyone for this piece of page.

Czech the relays I believe that in the Audi there is one that controls most of the converters, and if not, it can be commanded by a BCI unit, as in Peugeot I hope it is not that if it will not be very expensive Czech and let us know how you are doing.

Ok ... Sub 191919483 of Hella that is under the balante did not work well is the one eaten by the heater and other change and arranged.
Thank you very much friends.