I'm finishing up my motor swap and am having some issues with the electrical right now. So the engine harness on my new engine wasn't the right one for my car (1997 harness on a 1992 car/ECU). I swapped the harness from my old original (blown) engine so it fits the ECU now and everything hooked up to the new engine fine except for a couple plugs that the new engine didn't have. Anyway, I thought the car was finally ready to run, so I hooked up the battery and it started sparking a lot and smoking a bit from the negative terminal. Checked my grounds and cleaned them with a wire brush and am still having the issue. None of the electrical components come on in the car when I hook the battery up, and it constantly sparks from the negative terminal as soon as I hook it up. I don't know much about electrical stuff, but I don't see anything obvious that would be causing the issue. Tried searching, but all the results I got were people worrying/asking about the little spark that usually always happens when you hook up a battery.

 

Is it the cables that produce sparks?

 

You have a short somewhere. Most likely the power wire going to the alternator or the power wire to the starter. Since it's doing it without the key on, it's on the "hot" side of the charging circuit, so most likely it is on one of the main large power wires.

Ground side will have nothing to do with it.

Do you have a stock location battery?

Could be a pinched wire that's touching ground.

Dale

 

Already checked the alternator and it seems alright. I'll have to jack the car up to check the starter though. And yes, battery (and car itself for the most part) is stock

 

To my knowledge trying to run a 1997 harness on a 1992 car in this manner is a good way to start a fire. The 1997 harness is not electrically the same as a 1992 harness and I would not be connecting power to that car. The plugs that don't connect to the ECU... The 1997 ECU is totally different to the 1992 ECU and they don't interchange. Its not a matter of just leaving plugs that don't fit or don't have sockets, unplugged.

You need to find the correct 1992 harness or I fear things will go crispy... I would stop trying to connect power to it until you get a 1992 harness.

 

Edit- I realized you mean engine harness and engine loom plugs- you'll find that the 1997 uses the "black box" which has different solenoid arrangements modulated into one big box and different plugs. The 1992 has things more conventional like a USDM where it uses masses of vacuum hoses and different wiring. You can't really fudge or get past this difference with putting a 96+ harness on a 92 car. It likely won't run properly if it doesn't burn or short something.

 

The car is a 1992. The engine I swapped into it is a 1997. So I took the rats nest and wiring harness off of the originial 1992 engine and put it on the 1997 engine so everything plugs into the car fine