What's up guys!!
I had my ae86 running megasquirt2 for my 4age silvertop 20v . I was having trouble tuning and what not so I went back to the stock harness and ecu.

Recently purchased a clean tweaked performance harness with coil pack conversion.
That harness had the other car running and all. Harness was actually pretty new as well.

I then swapped it in to my ae86 and I go to turn the key and nothing. Just clicked at the relays. I check the harness and it had 12v at all points needed.
I think that something is interrupting the 12v to the starter and isn't letting it engage just don't know what. Pls help!!

Time to bust out the multimeter and wiring diagrams.
I would start at the starter.
You will need someone to try to crank it while you look for voltage at the signal wire on the starter. Also make sure you see 12v at the big lead going into the starter while they are trying to crank.
If the signal wire and batt lead both have 12v then the problem is your starter. If one doesn't then you need to chase the circuit back till you find power.

Yes sounds like a starter (relay) problem.I'd also start over there. Look into the workshop manual to know what you actually have to measure.

was this car an automatic?

I was indeed the starter relay. It had a wire clipped at the the clutch solenoid that lets the relay know the circuit is complete.

I have 5k idle and would like to know how everyone else is drawing a good vacuum for the bt map sensor