I've just recently switched from a Mallory box to an LTCC setup.

Prior to the switch, both my shift light and my MSD window switch stoped working. I assumed it was my mallory box, so I installed the LTCC. The car runs great and the stock tach works fine, but both aftermarket items still don't work.

I have the shift light and MSD window switch spliced into the tach signal from the PCM. I also tried splicing into the white wire that runs the LTCC (the old coil signal wire). Both wires showed voltage and are running thier respective stock parts without issue.

The shift light flashes upon start up and I have verified power and ground to the MSD window switch. The only test I haven't run is to try another aftermarket part off of the tach signal.

What could cause this? What else should I test? Any ideas?

 

I believe you need a tach signal adapter I believe MSD or Autometer make it.

 

Thanks for the reply. I happened to figure out the problem tonight.

I got fed up testing connections and such so I just ripped out all the wiring. Turns out one of my wires had a break inside of it. The new wiring fixed the issue.

I'll be headed to the track tomorrow to test out the new ignition.