Blowing fuse. Wire question. GL 1500

[Scaldedchevy]

Hello,

Bike:
88 GL1500

A couple days ago, I started blowing the same fuse. Fourth from the bottom. It carries the headlights, tach, neutral light, OD light on the dash.

As soon as I put a fuse in, it is blown.

So I finally traced the wire down that is getting hot. Under the seat. The coupler harness. on the right side, if you are standing in front of the bike. The wire is green, and is the very first wire on the top left of the harness.

The problem is, I have no idea what this particular wire carries. If I knew, I could pinpoint the problem and go to work, rather than tear down the entire wiring system. That is far too much of a job for me.

Can anyone tell me what this wire carries? It is obvious that it is the culprit. It is partially melted. All other wires are in good shape.

Any help is greatly appreciated.

Thank you
James Vallery

[virgilmobile]

I'll try to help.A couple of questions.
Does it blow the fuse as soon as you put it in or when the key is turned on.?
This white plug.I can't identify it in the schematics.How many wires are in the plug?
It appears that the "hot" wire is dark green.Can you confirm that and if it has a tracer color.
Does your bike have a trailer plug tucked up under it possibly shorting out?
If you disconnect that plug,will it still blow the fuse?
Reminder..Solid dark green wires are always a ground wire.

[Scaldedchevy]

Thank you for your help.

There are 24 wires in that coupler.

It does not blow unless the key is on. It will frank and run, but no headlights, OD light, tachometer, or neutral light. Today I soldered in a new section of the green wire that I could see had started to melt. Unfortunately that didn’t help. The back of the fuse panel looks good. No damage or burns. The fuse that is blowing is fourth from the bottom. It has a large white wire jumping to a relay.

I took the dash out today. I couldn’t find anything. You can physically feel that particular wire get hot when you turn the key on it you jump the fuse. I only do this for a second at a time, as I am working and trying to see if I have found the problem.

I don’t have a hitch, but that is not to say that someone didn’t have one before me. There was quite a bit of wiring done before.

Are you saying that somewhere there is something that has chaffed and is grounding, and I just have to look until I find it? I was hoping that wire would help me focus my efforts on a particular system. God help me.


Thank you again
James

[Scaldedchevy]

Oh, I forgot to mention. It has no tracer color on the wire that is getting hot. Just green. Top left on the coupler. Or bottom right, depending on which way you are looking at it.

[virgilmobile]

I think your going in the wrong direction.Head to the back end.
I suspect that if you unplug that connector the bike will still run.The green wire has power going to it through the plug back up the left side of the bike to ground.
There has to be something shorted from switched volts to that ground wire.
Example...Say a tail lamp filament shorts inside..Power then goes from the hot wire feeding the lamp right to that green wire...

[Rambozo]

If you don't have a wiring diagram, I strongly suggest you get one. The first place to look is any and all added accessories. Most often they are disasters waiting to happen. A short tracer can be a big help, but you can probably get by without, with just visual inspection and simple meter tests.

[Scaldedchevy]

Thank you very much I will get back on it tomorrow

[Scaldedchevy]

Thank you very much. I will get back to work on it tomorrow. What you said made me remember that my brother in law told me that I had a “light loose” on the back end. I was busy, and forgot about him saying it. I will check it tomorrow

[terryt]

Pull the plugs apart and check the terminals they may need cleaning. seems strange it getting hot and burning there

[WingAdmin]

I'm having trouble identifying that specific connector. Is it on the RIGHT side of the bike? Can you take a picture from slightly farther back to give a better idea where it is?

How many wires are going into that specific connector? It looks like ten, but I can't say for sure.

Generally speaking, solid green wires are almost always ground. I suspect you have a short elsewhere, and next to the fuse, that green ground wire (or more accurately, the terminal connected to that ground wire inside the connector) is the weak spot, so that's why it's heating up.

[Scaldedchevy]

Thank you for the input. I found today that without that wire connected, the starter will not turn over. But, everything else will light up. If the coupler is the weak spot, would it be advisable to by-pass the coupler with that specific wire, and just solderbit directly?

Thanks
James

[Scaldedchevy]

Here is a picture farther back, as requested.

[WingAdmin]

OK, that is definitely C10, which is what I had originally suspected.

It looks like someone might have already grafted a repair onto the green wire? I see heat-shrink tube in that last picture.

The solid green wire on C10 is definitely ground, and it's unfortunately ground for quite a few different things:

Radio noise filter
Air pump
Trunk side marker lights
Brake lights
Trunk running lights
Saddlebag lights

Also unfortunate - none of those have anything to do with the headlights or other dash lights you mentioned. In fact, I can't find any evidence that headlights etc. go anywhere near C10. I'm wondering if you may have two separate problems. Have you actually felt that wire getting hot, or just see evidence of it getting hot?

[virgilmobile]

How about the green ground buss connector by your left kneecap..A problem there and power may be seeking ground through that plug in the back.
Have a look through this posting..
viewtopic.php?f=6&t=22534

[Scaldedchevy]

Thank you sir for your reply,

The heat-shrink tubing is my own doing. I did that myself, after finding that the insulation had melted away on that particular wire. Answering your question, I can most definitely feel the wire heating up. When you turn the key on, within two seconds you can no longer hold on to that connection. It gets very hot, very fast. I have exhausted everything within my abilities. The only thing that I have not done is completely remove the bags, and the fuel cell cowling to see if the problem is somewhere in that area.

Thank you all so very much for your assistance. I am extremely grateful. This bike is the only thing in my life that I have to relieve stress. I know that the longer it sits, the more problems can develop with the carbs. I appreciate all of your input very much.

I was after this bike for over 20 years. When I finally got it, it had sat up for two years. It took $2000 just to CRANK it. But, it is my love. I am having to learn as I go. I have figured out many problems on my own, because there are less and less people that understand these bikes. But this problem is truly stressing me.

James

[Scaldedchevy]

Please pardon my ignorance, but, a bad relay can’t cause this issue, can it?

[WingAdmin]

Please pardon my ignorance, but, a bad relay can’t cause this issue, can it?

No, there has to be something that is drawing far too much current. Usually a short means a wire is pinched and is shorted to ground. However, in this case, the wire getting hot (that you know of) IS the ground wire. So this means something is shorting across the load - or the load itself is shorted. If a light bulb were to short out (or the wires leading to it shorted out), this could cause this type of symptom.

[Erdeniz Umman]

Please pardon my ignorance, but, a bad relay can’t cause this issue, can it?

There was an issue like this and the culprit was found to be a bad relay.
If the relay pins melted, there is a chance to make a short inside, since the +12v and ground soldering points are very close to each other as shown below.
Red dots are the gaps between the main +12v and the soldering points of the coil.

[DenverWinger]

A couple days ago, I started blowing the same fuse. Fourth from the bottom. It carries the headlights, tach, neutral light, OD light on the dash.

As soon as I put a fuse in, it is blown.

This with the ignition switch "on" I assume?

I don't have '88 schematics, but I imagine it has headlight Low beam and High beam relays, if you pull those it takes the headlights out of the circuit and this tester I'm about to describe will work.

Take a blown fuse and scrape away enough plastic at the corners so you can solder two wires to the contact blades, then plug it back in to the fuse box. Connect a high current 12v bulb to the wires, an old sealed beam headlight bulb would be best, a brake light bulb (1157) would work too. This will protect the wiring in place of the fuse, the light bulb will not draw enough current to damage any wiring, and you can probe around with the circuit "live".

While whatever is shorted is still shorted, the test bulb will glow brightly. Reason for taking the headlight relays out is the normal load of the bike headlights would cause the test bulb to light brightly WITHOUT the short and defeat the test.

When you've finally removed the short, the test bulb should go dim or dark.

If by chance the test light does not light or only lights dimly when you first try it, it is possible the headlight relays are the CAUSE of the short as Erdiniz described. Put a good fuse in #4, then replace the headlight relays one at a time to see which one blows the fuse.....

[terryt]

If you haven't already done it. I would isolate and disconnect all the wires that are running accessories or extra light cd or what else is fitted. then start testing

[newday777]

Here is a picture farther back, as requested.

Howdy James
I haven't been on in a while and saw this project notice in the monthly letter. I've had a bike that I had to work on for a friend last spring, in which that connector was burnt, which had other symptoms than yours, but must have a common link as that is the ground to the rear of the bike.

As Wing Admin has said that is the ground in C10. Have you unplugged C10 and tried to see if the fuse still blows or corrects the headlight problem? If it corrects the problem at the front, then you know the problem lies rearward of C10.

Reply back the results to continue....

[terryt]

Looking at the ETM for an 1989 and a 1995 the C10 white plug has 22 wires. you said your has 24 wires.

[peppilepew]

I can't tell you specifically what's wrong. What I can do is tell you that you don't need a diagram to find a direct short to ground. That's what you have. A component would just fry when asked to carry full fused capability. Disconnect the ground and install a circuit breaker rated slightly lower than the fuse that blows. Do you have an infared temp sensor? Harbor freight sells them quite reasonably. Now keep in mind that whatever is shorted is designed to handle large amounts of current. I would pull the headlight bulbs one at a time. The circuit breaker will break the circuit before the larger fuse blows. That will allow the trouble area to show up as a heat source. You should be able to find the area with the infared sensor, or your fingers.

[SlowTyper]

Check your [tailight] bulbs. One my be the wrong bulb. There are bulbs with two pins on the bottom -- some have 2 filaments and others have one. In the case of the single filament bulb with 2 pins, one of those pins is ground and the other is hot. If that bulb is inadvertently replaced with a single filament bulb that has only 1 pin, that one pin on the bulb will short out the 2 pins in the socket -- blowing the fuse!

[Scaldedchevy]

Gentlemen,

Thank you all so much for your assistance. I am happy to say that I found the problem today. The left marker light, under the rear saddle bag. The wires had worked close to the exhaust, and melted. The resulting contact was what all my troubles were. I soldered in new wires and connections. Thank you again. I was going to the front, but like one User posted, I was going in the wrong direction. Y’all are the best.
Regards
James