mikehayes

I am attempting to rewire my '84 tach/mpg gauge after a 16V engine swap. Looking at the wiring diagram it needs three inputs: the injector pulse to the black wire in the two prong connector under the dash, an unknown signal from the black and yellow wire in the same connector (used to come from pin 11 of the dme), and the injection pulse signal to the thin green wire in the 9 pin molex connector in the engine bay. When I give the thin green wire the signal directly from the green terminal of the coil, the tach doesn't work. I'm not sure why, given that it worked fine pre engine swap. I'm also not sure what kind of signal was in the black and yellow wire or how to replicate it. Does anyone have any info that could help me diagnose the problem?

mikehayes

Actually figured this out about five minutes after I posted this. The tach will not work properly given the coil signal alone, but when the green wire gets the coil signal in conjunction with the black wire getting the fuel injector signal, both gauges will function properly. Still not sure what the black and yellow wire delivers. If anyone knows I'd still be curious to find out.

ElRicardo

the black/yellow wire comes from pin 11 of the early DME and is the fuel consumption indicator signal.