I just swapped a 2000 b18c1(obd2b) in my 95 (obd1) LS and the tachs not working, anyone know whatto do? someone told me i had to splice into a wire on the dissy, but wasn't sure what color wires to what color wire and haven't found anything in my helms manuals yet or from searching on here.

 

I think the obd2 uses a different tach signal from the distributor.
Get a helms for the odb1 and odb2 and compare. The back of the guage cluster has a blue wire that controls the actuall tach display.

 

thanks