I have a MSD Window switch but i dont know what wire to tap into at the pcm.
It's on a 97 T/A m6,
I thought it was the Red wire harness on pcm with the white wire, which should have been A13, but i read a post and it said A25???
I tested both but the voltage was constant threw out the RPM.


What wire do i tie into, for the msd window switch to work, that reads the tach/ RPMs??

 

13 is the tach wire (white).

25 is the fuel enable wire and would be dark blue.

 

I tested the voltage on 13 and it was constant, around 4.9

 

I have not had to test the wire myself, but I know that it is the correct wire for the tach by all wiring diagrams (same in OBD-I and II). It may actually be a rapid pulse that the tach uses and not as easily read with a volt meter-not sure.

 

Thats all i needed to know, thanks