i just sold my 92 civic sedan to my friend. 2 days later the ecu fuse blew and kept blowing every time we turned the key on. so we swapped some parts off of my car to see if it would stop blowing...under hood fuse box, main relay, ecu. and kept blowing. so we went to the junkyard and got another underdash harness and swapped it. the car started up and ran for 5 days. and today it started doing the same thing. im tired of working on this car that is why i sold it. car is an automatic with a d15b swap with the auto d15 ecu i forget what it is. please help me figure this out. he said today it done it when he realized it was in drive2 so he switched to drive and then it blew and now it just keeps blowing.

 

what about a bad injector wire?

 

Does unplugging the main relay, ECU, IACV, fuel injectors, EVAP purge solenoid valve, or O2 sensor prevent the fuse from blowing? Test each one at a time.

 

unplugging the main relay prevents it from blowing. we unplugged the harness running from just under the driverside dash that runs to the tail lights, the 3 plugs that run to the dash for the gauges and things, and we unplugged the ecu and and all the conectors running to the under hood fuse box except the one that has the wire running to the main relay. and it still blew. so i ran a new wire from the main relay to the connector that plugs in the under hood fuse box and it still blew, so im thinking its one of the other 6 wires that plug into the main relay but we replaced the whole underdash harness so now im thinking injector wire. and it only does it on the run position of the key. the only thing i can think is to test resistance at the hot side of the fuse and jiggle wires on the engine harness until it shows resistance and maybe ill knw about where the bad wire is if that is what it is....i havent tried unplugging the iacv, injectors, o2, or purge control yet. is that something i should try and report back?

 

Yes, that's why I suggested it.

 

Hey I'm the owner of the Civic in question. I'll report back later tonight on each of those things. First I must get a multi meter and some more fuses from the store.

 

Good news everyone! I went and started to try the different ideas that RonJ had suggested, when suddenly BAM it hit me. I had found the cord from the O2 sensor tangled in the radiator cooling fan and while removing it thought to myself hmmm thats pulled out a bit. I should cover that. It was the O2 Sensor grounding out this whole time.

The two spots were where it was grounding out.
Its all better now. I feel kinda like an idiot.
Thanks a million RonJ@HT I will not forget that you were willing to help so quickly.

 

Congrats on finding the fix.