Blowing Ignition Fuse

I just got my wife a 1982 XJ650. It is blowing the ignition fuse when you turn on the key. I have used an ohmeter and tracked it down to the ignition control box. It is grounding from the R/S coil wire to the black ground wire connection. Is this a common problem for these bikes? Also, the previous owner replaced the wiring harness with one he bought on ebay. He says it was advertised as an 82 harness. I know that they changed the harness after 81 and was wondering if there is anyway I can make sure this is an 82 harness.. I hate to replace the ignition module only to burn the new one out because it is the wrong harness..... Any thoughts, ideas, clues??

Thanks

 

First order of business is to confirm the wiring harness is correct for your application, a long and drawn out affair if your alone and don't know how to chase wires. Get your hands on both years of schematics and start ringing out the harness, point for point. I had to modify my 81 750 Seca to accept the instrument cluster off of an 82 by adding a ground to my harness. Good luck and get those schematics! We can chase it together, I've got my book. More to come.

 

I have a Haynes book and it has the schematics in the back. I also have the old harness now. Got it from the previous owner. Just by looking at the connections and the color codes of the wires, it looks the same. I will do some more checking today. I want to make sure everything is right before I put a TCI in, dont want to burn up the replacement!

 

Have you checked the original harness for damage? I'm thinking that the harness was replaced because of the difficulties your experiencing. I'd give the old one a good looking over (and let me know if you want to get rid of it, I harvest old connectors to rebuild harnesses). Ohm out your old TCI as well, see if it is in fact dead. If you find the TCI is still within limits, your going to have to look elsewhere (like a bad ground or something, don't laugh, had a fella offer me a perfectly good Honda for $50 because he didn't reattach the ground wire on the transmission). Best of luck!

 

I have the old harness. Lots of bare wires in it. It is pretty messed up. I am going to use one or two connectors off it I think, other than that you can have it once I make sure this bike runs with the harness that is in it! LOL

I tested the TCI between the connection for the R/S coil wire and the ground wire. It has straight continuity there. O ohms or resistance. My haynes doesnt give a proper test for the TCI, it just says to rule out everything else, and then to consider the TCI.

The way I tested it was, I knew the ignition fuse was burning, so I hooked one ohm meter lead to the fuse box and the other to ground. Then using the wiring schematic, I systematically un-connected one connection at a time until I lost the short. I ended up at the TCI. I did ohm out the primary windings on the coils just to make sure they are good, and they test properly. I am pretty sure the current wiring harness is correct, and my new/used TCI should be here in a day or two. Not even sure if it is good though cause it is a used one I found on ebay. I have been reading on here alot of the post and have not came across anyone mentioning the TCI causing the ignition fuse to blow. I am wondering if the other harness with all those bare spots caused this problem, and if I have a unique problem.

That is what is worrying me the most about this, no one else has mentioned having this problem. I am hoping it is the correct problem and maybe I am one of the few to have it, either that or I am barking up the wrong tree.... er, wire I mean.. LOL

Can you point me in the right direction for the proper way to ohm out the TCI?

 

Since the Nice folks at Yamaha conveniently/intentionaly neglected to provide any information on the TCI, folks have had to muddle through testing them alone. One fellow even went so far as to fix his own and chronicled his efforts for posterity (I believe you can find his recount from a link I posted a long time ago). I'm not having any success finding the link to his site but I do know it's out there. Go to our links section and look for TCI info on the second page. An issue that is mentioned is the occurance of cold solder joints. Open the box up, clean the board off with alcohol, and do a very close visual inspection for cracks. I wish I could be of further assistance. When you do finish up, I would be glad to get my hands on the old harness, keep me posted. Best of luck to you again.

 

Try this site for info:

http://www.jetav8r.com/Vision/TCIRebuil ... build.html

 

Thanks, I will give it a look!!

 

That was the link Nick, your a blessing to us all! How did you find it? I thought I had it bookmarked in my motorcycle folder. Good on you, as I'm always saying, what would we do without you? Hey Dgmid61, would you perhaps be interested in donating your dead TCI to science? I was thinkin' while I was takin a shower that I should see if I can't reverse engineer one of those things. I've got the books covering TTL and CMOS chip schematics so I should be able to rebuild it (provided the factory didn't wipe out the chip numbers or get custom proprietary chips). I'm up for postage.

 

I would give it to ya with no problems, cept that I decided to try to take it apart myself last night BEFORE Nick sent me that web page.. got a little anxious trying to get the board out of there that I broke the board... You can still have it if you want, but its broken right where the connectors come out of it. Not sure you can do anything with it now or not..

 

I can rebuild it, one of my specialties. No problems, I'll PM you with details. Hope your "new" TCI fixes the issue.