I just bought an 81 280zx as a barn find, after some cleaning I hooked up a battery... it was like a Christmas tree on the dash, lights flickered, bell dining fast/slow, gauges twitched. Key was off and out, I unplugged the ignition and that didn't stop it. Engine cranks over, has spark, Fuel etc. But I didn't continue to start it from fear of causing a meltdown. What would cause this? The ecu looks mint, fusible link has maxis in it(maybe the cause), buses are all good. All of the wiring looks fresh inside under the dash.

 

Sounds like a relay is racing (on-off). Can you hear a fast clicking above the bells and whistles? I have an 82, same car but I haven't got into the electrical much. Let me spend some time with the E-diagram and get back.

 

Yep I think I tracked the issue down to the ignition relay and accessory relay, located above the buss fuses on the passenger side. I swapped em out with a relay I had available and problem solved. Note that it is easier to access these 2 relays by taking out the glove box, they're located right behind it.

 

If the issue returns it could also be the ignition module behind the key hole. Its an $18 part, but my old one would let me remove the key while the car was running. It would also not fire the fuel pump or make the relays click like crazy. That and a corroded negative battery cable solved many of my random electrical problems. Mine is an 83ZXT. I thought my relays were bad too (same ones you swapped) but they seem fine after replacing that ignition part.