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OK, I screwed up big time. I was trying to install a new amp in my car for a subwoofer and I tried to go through the firewall next to the main wiring harness that runs from the under-hood fuse box to the interior -- you know, the one that powers EVERYTHING. In the process, I cut or damaged a wire (or wires). So now, my power locks, HVAC controls, stereo, and remote lock/alarm do not work. However, my horn, interior lights, sunroof, and the buttons for the A/C and rear defrost below the stereo still work (or at least turn on). I've checked all the small fuses (7.5 through 40 amp rating) and none are blown. I successfully found and spliced an orange wire that I cut, but I can't immediately find any others that are cut.

Does anyone have a wiring schematic or any advice as to what wires I have to splice to get this running again? I really don't want to drop $350 on a new main wiring harness.

I have an '04 EX coupe. Any help would be greatly appreciated.

 
Rep Power: 353

its ur fuses. thats why they're there. u have one in the engine bay and one under the steering wheel.

 
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It's not. I checked both fuse boxes, pulled out each fuse, and inspected them. None are blown.

 
Rep Power: 353

then u blew you ur multiplex control unit.

search and you'll find results for it.

///////edit

did a quick search for you

https://www.civicforums.com/forums/2...trol-unit.html

rep me +1 if you found it helpful.

 
Rep Power: 0

Interesting. I'll give it a look.

 
Rep Power: 309

If wires were cut you should be able to match color for color and splice in a new small sections of wiring... getting to the harness may be another story.

 
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My problem is that it's in a ridiculously hard to see area -- basically, the small space between the rubber grommets on the firewall and interior. I could see one wire that was visibly cut, so I spliced that one. I picked up a Haynes manual and it says both the power locks and the stereo are fed by a white and red wire. I might try splicing that one next in case it got damaged.

 
Rep Power: 309

If the fuses are o.k. I would check for other broken wires. You may have to unwrap the covering for better view. You may be able tug on the wires one at a time to see if they are broken (one side or the other)

 
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I found one other broken wire, so the HVAC system is now working. Power locks, remote lock unit, and stereo still aren't working. The stereo and the power locks have a thick white/red wire in common that isn't broken as far as I can tell, so I think the MCU is fried. Is there any way to test it before I replace it?

 
Rep Power: 309

Double check Fuse #9 / 10 amp called "back up" in under-hood box.

If it is o.k. check the factory audio harness WHT/RED lead for constant power.

For the windows, the (+- or -+ UP/DOWN) voltage from the master switch is fed through the individual windows switches and a voltage source is supplied to the individual ones for remote operation. Best to measure voltage at the inop window IMO.

Don't forget the window lockout button on the master switch.

 
Rep Power: 353

nope. and they fry easily if u short them. ive replaced mine twice on my civic because of my stupidity when i first started doing audio.