Hello all,
2008 Honda Fit Sport GD3

I'll give you the backstory - was going to a buddies house to help him fix his car, got a battery light while I was driving - started losing power steering and other electronics and pulled off at Advanced Auto Parts.

During the drive I observed the Dashboard drop out, watched the radio turn off, lost the ability to turn the car easily, so lost power steering as well. I got the car parked, got them to test the battery, it tested as Good according to their test unit. Okay, so alternator (backed by the observation that when it was running and I revved it, the voltage did not go up or down). As insurance I had them put the Battery on the charger while I went out.

Went to LKQ because frankly I didn't have the money to get a new alternator at this moment - pulled an Alternator off of a 2007 Fit Sport - I figure it should be the same alternator - 4 pin plug, plus the bolt on ground. Swapped it out in the parking lot, reconnected the battery + to + and - to - and I faintly smelled a burning smell - that's not good, turn the key, very very faint dash lights, worse than when I went out. The smell got more noticeable and I pulled the wire off of the positive terminal - smelled around in the engine bay and interior, smell is only coming from the interior.

My concern is I just fried the ECU or other electronics in the car, I'm kinda at a loss of words here because the car was fine until I got the battery light, started and drove just fine, no drop-outs until today, has anyone else ran into this before? Any ideas on what to check as far as Main wiring goes? Any troubleshooting tips would be appreciated as well.

I'm going to have to get the car towed home, joys! But I'm planning on giving it another stab, maybe it ate a relay or some stupid like that.

​​​​​​Thank you all for your time in advance!

 

This is my current thought process on why I may have smelled burning electonics/plastic in the car and then had no signs of life.

During the drive I experienced a good number of electrical drops - when I went off to LKQ the car was dead and would not start, clicked a couple times while I tried to start it. Had Advanced Auto Parts charge the battery on the suspicion that it had died.

I may of had a relay locked in the closed/open Position, when I reconnected the battery, it delivered the power through the 'powered' relay to the next component in line. Voltage drop/fluctuations in the car may have "welded" a contact in a relay in the powered state, then when the car was off, a relay expected the systems to be online and fed current to an unpowered system completing a magic smoke trick.

In sum the battery may have been connected for maybe 5-10 mins in totality. I visibly saw smoke in the sunlight after opening the doors all the way out to vent the smell.

I'll check on it tomorrow as a fresh day will shed more light, but my current theory is to check for burned up sections under the dashboard, that sort of stuff. Cross-check what I find with the wire diagrams - maybe find a culprit. If the wiring is okay and not compromised it may be able to be saved

But frankly, if it lets the smoke out, in my experience, it's hard to put the smoke back 'in'. I may end up writing off the car depending on what I find tomorrow.

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I'm curious as to what you found. I'm an electronics engineer and got an "electrical writeoff" 2009 fit going as my daily driver as of last year. My job is to get the magic smoke back IN the circuit!

 

So I did probing and battery testing, battery had passed its test before I made this post and after I made this post the battery had failed outright. Couldn't even register on the AA Tester. All of my fuses tested good, used a multimeter on the heads of every single fuse and continuity tested all of them as well, nothing failed or popped, I was able to get the life back in it with a fresher alternator and a new battery. Something about the one I put in it initially probably had something wrong in the Voltage Regulator on the Alternator side.

Checked all the PCMs and ECMs for melty wires or anything out of the ordinary and thankfully nothing evil happened. My magic smoke appears to have been the battery finally giving up the ghost.

For your particular issue, I'd start at the battery, check the engine fuse panel for fuses and relays, then disassemble the underside so you can peep the bottom for bad/melted wiring, then check the internal fuse panel to see if anything had failed there.

I'm sure with your background those have already been checked but you could be dealing with a missing connection or a bad body ground as well, those are things I had to make sure were scrubbed clean.

TLr, battery fried itself let out the smoke, big dumb battery wasn't a fan of the crappy alternator I sourced.

Best of luck to your issue my friend and thanks for commenting so I can close out my thread properly and not leave people hanging!