Hey guys, I have a 86 GT here and I cannot get the stock tach to work.
Simple combo. Holley term X. 6al. MSD 8920.
Tach output on the box goes to white. Violet goes to c246 pin 12(dg/y)
Ground is the stock ECU ground in the pass side kick. Fuse 18(hot in run/crank) kicks on the adapter.
Msd tach output tests fine with aftermarket tach. I’ve tried 2 tach adapters-no change. I’ve tried different clusters. No change. Tach does not move. What am I missing here?
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