Wires melting under headlight...

Kiesster · 10-05-2009, 12:49 PM

Hey guys,

I just joined motorcycleforum.com and just got my first bike about 5 months ago. Since I've had it, I've been riding daily with no problems whatsoever. BUT...

I had a small problem awhile back right after I got the bike. It wouldn't start. I'm not an expert when it comes to mechanics and electrical work, but I have a good head on my shoulders and am quick to figure things out. I had power (headlights, dash, etc.) but pushed start button and.. nothing. My first thought was, weak battery. Got a new one, threw it in, same deal. I started checking all fuses and connections, and bingo, there was a connection loose in the (sub harness?) plastic connection box located under the headlight, next to the horn. Plugged it in and viola, bike starts. I figured out when the handlebars were turned too far, the connection didn't have enough slack and the plug came out. Pulled the wire out a little bit, gave it some slack, and zip-tied it so it wouldn't move.

The bike ran fine all summer, until last week. Went out to start the bike and take an afternoon ride, and... no power whatsoever. I began checking power (one of those little pens that light up, the name evades me) and started at the battery... power all the way up to that little box under the headlight. This was a different connector, and it was loose. Plugged it back in, and bike ran. Then, these wires started overheating and melted (yes, melted) the connection points of these wires. I began doing a little investigation, and found that my main fuse (30amp next to battery) was not there, instead a folded piece of foil as a bypass. So, did a mod to it to replace the dogbone fuse and put an inline fuse in place.

I put the wires under the headlight back in place (without the plastic connection, since it was melted) and I still get power, and the bike still starts, but these wires are overheating like crazy....and now I'm stuck. I've already had a few suggestions to clean all of the ground connections, and this still has not solved the overheating wires. Any ideas??

Plumcrazy · 10-05-2009, 03:27 PM

My first thought is to replace that wire on both sides of the plug...and I mean all of it. Once it overheats, the wire starts to act like a resistor and heats more which makes it act like a resistor and overheats and ............well you get the idea.

Second, whatever those wires go to is either very corroded or shorted out...drawing way too many amps, which leads to the above

Wayne S

tylernt · 10-05-2009, 08:25 PM

Quote:

Originally Posted by Plumcrazy

My first thought is to replace that wire on both sides of the plug...and I mean all of it. Once it overheats, the wire starts to act like a resistor and heats more which makes it act like a resistor and overheats and ............well you get the idea.

Second, whatever those wires go to is either very corroded or shorted out...drawing way too many amps, which leads to the above

I concur. It's a lot of work and I'm sure it's not what you want to hear, but... at the very least, unwrap those overheating wires all the way from end to end to check for brittle/melted/breached insulation.

Kiesster · 10-06-2009, 02:20 PM

Well last night I took off the tank and seat, and the wrap around the wire harness. I followed the wire up from the battery all the way to the point of the problem. The wire seems to be completely intact and not exposed anywhere.

I'm wondering if the problem could be in the rectifier? Maybe it's not regulating the amperage from the battery and it's surging? These two sets of wires (the ones overheating) are the main power and negative for the main power.

I ordered a new harness off ebay, and should be getting it later this week. I'd like to try to narrow down the problem before I install the new harness, because I'm afraid if I just throw a new harness in there, it will do the same thing. Any more ideas?

tylernt · 10-06-2009, 02:27 PM

If those are the main wires, then the problem could by anywhere on the bike in any of the other circuits feeding from the main.

As for the rectifier, you can test the voltage easily to make sure it's in the right range (less than 15V, maybe 16V). You can test the amperage too but many cheap ammeters don't go over 10A and it sounds like you're flowing a lot more than 10A which would fry your ammeter.

Berktin1984 · 10-23-2009, 09:34 PM

I would just go through and replace the entire wire harness it's just safer that way. might not be the cheapest or easiest fix but if you melting wires keep in mind there are wires that run below the tank and thats very close to fuel lines for my comfort.

David 1 · 10-23-2009, 10:07 PM

$160 for a new wiring harness for that bike. But they are right. I think the bike is worth it.
It will solve those problems (wires).
Particularly at 23k miles. Many miles left on that bike. So fix it right.
dc

Biker Dash · 10-24-2009, 04:56 PM

I agree that you should replace the whole harness. That would also prevent many potential problems from ocuring from running an old harness that has had issues. Also, replace that connector box. It looks to me to be destroyed. Finally, find the guy who used that piece of foil instead of a fuse and give him thirty lashes with a wet noodle. What do you have for a bike anyways Kiesster?

Kiesster · 10-24-2009, 05:29 PM

Thanks for the help guys. I ended up getting a used harness off ebay for $15. I was going to take all your guys' advice and replace the entire harness, but as I was midway through I ran into a problem.. The connections weren't lining up. I ended up finding the culprit though.. there was a connection point that had been heated up too much (most likely from the foil "fuse") and there were wires touching. I cut off the connection from the new harness and replaced it, and the wires are no longer overheating.

I got real excited after doing this and decided to take it for a ride (dumb, I know, but I hadn't ridden over a month). So I was cruisin around for a solid 30 minutes until I lost all power again.

The connection box under the headlight (the pictures I had posted) was pretty much totaled so I had to order a new one from the local Honda dealership. $60 for a plastic box with a few metal rods goin through it! Anyway it should be in by Monday and *hopefully* I'll be set.

Animedevildog, it's a 1984 Honda Shadow VT500C. And believe me, I sent the guy I bought it from a very unhappy email.

Biker Dash · 10-24-2009, 05:39 PM

NICE ride Kiesster! As you can tell from my avi, I ride a Shadow myself.

I hope that you get it fixed. It sux not being able to ride... *glares outside at the pouring rain*

gurhy · 12-31-2009, 11:01 AM

Ah cool, that helps with some of my problems thanks for that I can get my other bike done up more now

10-06-2009, 02:27 PM	#5
tylernt Special Member Join Date: Apr 2008 Location: Idaho Posts: 663	If those are the main wires, then the problem could by anywhere on the bike in any of the other circuits feeding from the main. As for the rectifier, you can test the voltage easily to make sure it's in the right range (less than 15V, maybe 16V). You can test the amperage too but many cheap ammeters don't go over 10A and it sounds like you're flowing a lot more than 10A which would fry your ammeter. __________________ '07 Ninja 500R, formerly '81 Yamaha XS400

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10-05-2009, 03:27 PM	#2
Plumcrazy Psychotic Reader Join Date: May 2008 Location: Beautiful Ozarks in the middle of Razorback Country Posts: 639	My first thought is to replace that wire on both sides of the plug...and I mean all of it. Once it overheats, the wire starts to act like a resistor and heats more which makes it act like a resistor and overheats and ............well you get the idea. Second, whatever those wires go to is either very corroded or shorted out...drawing way too many amps, which leads to the above Wayne S

10-06-2009, 02:20 PM	#4
Kiesster Motorcyclist Join Date: Oct 2009 Location: Mentor, OH Posts: 10	Well last night I took off the tank and seat, and the wrap around the wire harness. I followed the wire up from the battery all the way to the point of the problem. The wire seems to be completely intact and not exposed anywhere. I'm wondering if the problem could be in the rectifier? Maybe it's not regulating the amperage from the battery and it's surging? These two sets of wires (the ones overheating) are the main power and negative for the main power. I ordered a new harness off ebay, and should be getting it later this week. I'd like to try to narrow down the problem before I install the new harness, because I'm afraid if I just throw a new harness in there, it will do the same thing. Any more ideas?

10-23-2009, 09:34 PM	#6
Berktin1984 Verified Join Date: Oct 2009 Posts: 26	I would just go through and replace the entire wire harness it's just safer that way. might not be the cheapest or easiest fix but if you melting wires keep in mind there are wires that run below the tank and thats very close to fuel lines for my comfort.

10-23-2009, 10:07 PM	#7
David 1 Senior Member Join Date: Aug 2008 Location: Los Angeles, CA Posts: 1,460	$160 for a new wiring harness for that bike. But they are right. I think the bike is worth it. It will solve those problems (wires). Particularly at 23k miles. Many miles left on that bike. So fix it right. dc

10-24-2009, 04:56 PM	#8
Biker Dash Site Brony and Troll Eater Join Date: Oct 2009 Location: Waterville, Maine (USA) Posts: 7,603	I agree that you should replace the whole harness. That would also prevent many potential problems from ocuring from running an old harness that has had issues. Also, replace that connector box. It looks to me to be destroyed. Finally, find the guy who used that piece of foil instead of a fuse and give him thirty lashes with a wet noodle. What do you have for a bike anyways Kiesster?

10-24-2009, 05:29 PM	#9
Kiesster Motorcyclist Join Date: Oct 2009 Location: Mentor, OH Posts: 10	Thanks for the help guys. I ended up getting a used harness off ebay for $15. I was going to take all your guys' advice and replace the entire harness, but as I was midway through I ran into a problem.. The connections weren't lining up. I ended up finding the culprit though.. there was a connection point that had been heated up too much (most likely from the foil "fuse") and there were wires touching. I cut off the connection from the new harness and replaced it, and the wires are no longer overheating. I got real excited after doing this and decided to take it for a ride (dumb, I know, but I hadn't ridden over a month). So I was cruisin around for a solid 30 minutes until I lost all power again. The connection box under the headlight (the pictures I had posted) was pretty much totaled so I had to order a new one from the local Honda dealership. $60 for a plastic box with a few metal rods goin through it! Anyway it should be in by Monday and hopefully I'll be set. Animedevildog, it's a 1984 Honda Shadow VT500C. And believe me, I sent the guy I bought it from a very unhappy email.

10-24-2009, 05:39 PM	#10
Biker Dash Site Brony and Troll Eater Join Date: Oct 2009 Location: Waterville, Maine (USA) Posts: 7,603	NICE ride Kiesster! As you can tell from my avi, I ride a Shadow myself. I hope that you get it fixed. It sux not being able to ride... glares outside at the pouring rain

12-31-2009, 11:01 AM	#11
gurhy Newbie Join Date: Dec 2009 Posts: 4	Ah cool, that helps with some of my problems thanks for that I can get my other bike done up more now