gojoe

I am trying to fit an electrically operated led boost gauge to a 1979 930. I was told I could connect the two operating wires in parallel with the two sensor wires on the back of the tacho which resulted in the car not starting. There are four wires on the back of the tacho : No 1 = ground No 4 = +12V Nos 2+3 are the operating wires for the tacho and the inbuilt boost gauge. Where do these two wires get there signal from ? They arrive together in a black covered sleeve but I can't trace them to their source. How does this boost gauge operate electrically and do I need a extra sensor to operate the additional led gauge.

Thanks in advance for any help

A930Rocket

Forget the electric boost gauge and install a mech one instead. Much more reliable.

Sorry I don't have a better answer to your question.....