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Discussion Starter · #1 ·
Hello friends, i’m posting today because i’m having some electrical issues with my s13. The car has a sr20det swap. This thing keeps toasting 62 redtop ECU’s and i’m trying to get to the bottom of it. I’m no stranger to working on my cars, but know very little about how electrical systems work. If someone with knowledge on the subject could give me some pointers, that would be much appreciated. I’ve been researching for days but haven't come across any articles on my situation.

I’ve owned this s13 for under a year and taken it to one track day. The car ran fine until after an hour of driving, I spun out and the car would not run. It would fire up, run very rough, and die. After troubleshooting every component, the car started up totally fine when I replaced the ECU. After speaking with one of the previous owners, he said the car had gone through many fried ECU’s for the same reason. I’m trying to figure out what could be causing this.

The shop that sold me this car gave me an entire vehicle harness to replace. However, after closely inspecting, it seems this new one is quite a bit different. I can sense disaster if I rip my existing chassis harness out and replace it (it’s a little over my head). For starters, the engine harness and the rest of the chassis harness are intertwined when it runs by the fuse box down through the front of the car. On my current one, they are separate(wiring specialties sr20 engine harness). Also, my replacement harness has a smaller ECU pin connector (maybe a KA harness?)

I am wondering if there are troubleshooting steps I can take to try and solve this ECU frying issue without having to replace all the wires in the car? Use a multimeter to trace where the electrical surge is coming from? Try to find loose wires that could be grounding out? Would little messy exposed wires cause enough surge to kill my ECU time again?

On a possibly related note, the car has a very severe parasitic draw. The battery will go dead in 15 minutes. That draw goes away when I remove the 75A linkable fuse in the fuse box. This is labeled the alternator fuse. The car will run without this fuse, but no electrical components will work (tail lights, radio, gauges, etc..). I’m thinking that this draw could be caused by a bad diode in the alternator? Allowing the electrical current to flow backward when the car is shut off? Or maybe something else? Could this in away way be linked to the ECU killing issue?

Thank you very much for any advice!

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