Hello there. I am having an electrical issue with my 1994 Civic EX coupe. I believe I may have shorted something in my electrical system because last night my stereo would no longer turn on. Anyway, I'll go over the facts of what I know first:
1.) Checked all fuses, all are good.
2.) Stereo and cig lighter are on the same fuse. Cig lighter still works.
3.) My pioneer head unit as well as two other aftermarket headunits I tried will not turn on.
4.) Double checked the harnesses and fuses for all headunits tested. All are fine.
5.) Checked with a voltmeter and am getting 12V on the red power wire at the radio harness.
6.) Blue/Wht stripe (Constant power) is only getting ~5-ish volts. LOW
7.) My FACTORY civic cassette deck DOES still work fine, but other headunits won't.
8.) I'm pretty sure that while I had the headunit pulled out last night to change out my broken heater control I accidently sparked the blue/white-stripe (constant power) wire onto the chassis.

So why the hell does my stock cassette deck work fine but my other aftermarkets stereos don't? The blue/white-stripe wire (constant) like I said is a very low voltage but I don't see why that would affect it. The pioneer headunit I was using didn't even use the constant power on it's own harness. So if anyone has any input I would greatly appreciate it.

 

you can hook up an ammeter in series with the battery and check the rate of drain. If it is high, start pulling fuses to see if you can get it to drop. That will tell you which circuit is draining power (if any) It might just be a problem with your aftermarket stereo.

I would try just wiring up the stereo directly to the battery with only the necessary wires to turn it on (ex constant power, switched power, and ground) see if it turns on then.