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Discussion Starter #1
I recently got my 79 cx 500 custom out of the tool shed and got after it, hadn't been out in ten years. Did all the regular expected things, carbs 3 times on and off, rebuilt front master cylinder, and a few other expected things. Didn't have a proper battery at the time, so was jumping it with my Goldwing batt. Some how managed to cross the jumpers and a few wires right in the battery box vicinity got hot, repaired them. Now, here's what I've got, turn the key off, headlight, oil pressure light, and neutral light are staying on. A neighbor suggested maybe I fried a diode when crossed the cables. She is running quite well, does everything she is supposed to do, other then have extra lights staying on, and unhooking the battery isn't a good long term every day solution. I'm weak in the electrcal area, so any help or suggestions will be appreciated. BTW, I do have a fairly complete donor carcas, but, a little newer if that gives anyone an idea as to what I might try. Thanks in advance for any help, Kurt in central MI.
 

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I think you have fused the red wire that supplies the ignition switch with power to one of the black wires which are switched 12 volt from the key switch therefor bypassing the key switch.

Inspect all of the wires carefully.
 

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There is only 1 diode in these bikes. It is in the circuit that allows you to use the starter motor with the transmission in gear if the clutch is disengaged and there is not supposed to be power in that part of the wiring (or anything else other than the red wire Phreak mentioned) when the key is off.

I'm pretty good with wiring but I would probably not spend a lot of time trying to fix a wiring harness that had been heated enough for the insulation to melt enough for something like that to happen. I would not trust that there were not hidden problems elsewhere in the harness without removing it from the bike, opening it up completely, examining every wire's insulation from one end to the other.
Replacing the entire harness would be a smaller job. What year & model is the "donor carcas"? Bikes in this family came with 2 different ignition systems and a few other variations between models but if it is close enough you may even have a suitable harness to install.....

BTW: Welcome to the forum. Please add your location to your profile and your bike's model and model year to your signature so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).

And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and aside from deterioration while in the shed it may or may not have had the maintenance necessary to keep it safe & reliable before that so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. I'd tell you to check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet) but if it was in the shed as long as you say new tires are a given. If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).
 

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Discussion Starter #5
Lights are out now. Thanks for the help. Had some wires fused together above the battery area and before it got into the main harness. I was hesitant to open up the original harness, just needed the little push from you guys. Thanks, Kurt

Don't know where to post this, so, here goes. I'm 30 miles north of Lansing ,MI. have too many bikes,
2000 1800 GW
81 1100 GW
79 1000 GW
79 CX 500 C
7? CB 450
lastly gorgeous little 80 Twinstar 200
 
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