Indianapolis 7922
 

Hi

Just had Indianapolis 7922 installed into my S, however sat nav side doesn't work, took back to installer and they state A1 speed dependent volume control is the lead required for speedo sensor - however as I get readings on x and y satellite positioning but nothing on speed I am not sure this is correct - anyone able to advise or let me know where to take this reading from, FWIW they also insist there is no input required for A2 reverse light - is that correct?

Any help gratefully received.