LX Electrical Issues

svjfm

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I recently disconnected the battery to run a new head unit to the car and everything was going well. I got everything hooked up and went and connected the terminals back onto the battery posts. I started the car and there was a party of lights on the dash (VSA, VSA OFF, TPMS). Apparently, this is normal after unhooking the battery for an extended period of time and the dash lights should turn off after some driving. I drove around for a while and the lights would not turn off. I turned the car on and off again and the lights still showed. So I disconnected the battery again for about 15 mins and reconnected everything. This time, the lights went away after seconds of driving but now I had a "check charge system" message instead of my mileage. I went and got my battery and alternator tested and everything was normal, (12.5V off, 14.4V with engine/accessories running). Funny enough, the message did go away after driving off post-test. I thought this was the end of my problems...

I parked my car and opened my door before turning off the engine. I move the key from the on position and my dome light turned off. It was strange, because the dome light was working before I turned my engine off. There also was no courtesy chime of my key being in the ignition, and no white lights above the instrument cluster. Mind you, my 12v accesory port and radio are still operational in the acc position. I went and tested a bunch of things now that I saw these issues come up. My trunk button no longer opens, nor do the door locks. None of my exterior lights would turn on with the car off either. I turned the car back on and everything was working again. A new thing I noticed with the car on is I lost my auto headlight functionality. I wanted to grab lunch so I decided I'd come back to it later but this is when I realized I've also lost my keyless entry functionality (can't unlock/lock doors or open the trunk with my key). I had to turn the car back on, lock the doors+fuel door that way, and manually lock my driver's door with the car off. The ONLY thing that I've found doesn't work with the engine running is the auto headlights. Is there a circuit that connects all of these things when the car is off? Just so I know where I should begin to look? I've tried researching this but I haven't found anything that pertains to this specific issue or (potentially) circuit. Is there a fuse tied to the auto headlight function? I don't think a blown fuse could be a cause if nearly every function I lost is restored with the engine running.

TL;DR- Disconnected battery to install new radio, new dash lights showed up after reconnecting. Disconnected battery again, got "check charge system" message. Tested battery and alternator, all operating within acceptable range. Message went away after continuous driving. Lost several functions that would normally work when ignition is not in ON position. Functionality is mostly restored when key is in the ON position.





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BrandonSmith

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Check ALL fuses under dash and under hood. Generally a good place to start. Also, if something is wrong after changing something, change it back and see if the issue persists.
 

shoegazer

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The first thing that pops up in my process is that the Honda Force has been disturbed by *something* with your new stereo. Checking fuses is always a good idea. And swapping out an old battery when you have electrical gremlins is often a good first step as well. There's more than one story here where the disconnection/reconnection was the last gasp of an otherwise working battery.

And I just gotta' say this... Thank you for a well written, concise, and clear description of the situation and the process.
 

ryanfk7

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Honda systems are getting more touchy with aftermarket parts like higher end vehicles. They want you to use OEM so they make errors occur when they don’t see same parameters. My guess is that the new head unit is drawing a different voltage/current so the system thinks something is wrong. Every time I installed new electrical items, the same lights occurred for me as well. I did track days and miles it took to disappear and it was different every time.
 
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svjfm

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It snowed overnight over here so I left the car alone and instead did some research about what could be connecting all of these systems together, and I came across an Odyssey and a 7th gen Civic forum post that both referenced a BACKUP (10A) fuse in the fuse box under the hood compartment.

I had pulled out fuses on Thursday due to the check charge system error that I heard could be triggered by bad fuses. I looked for burnt ones but didn't find anything. I decided to take a look again this morning and I found that the 10A fuse for the backup was missing. In the haste of testing fuses the other day, I ended up placing that 10A fuse in a slot that wasn't connected to anything. I moved it back to where the backup fuse should be and everything works again!

This prompted me to check all the other fuses in the box and thankfully nothing else was out of place and had the correct amp rating.
 

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