Weird Electrical Problem. Not sure where to turn

[RustRider]

Hello, I am new to this forum and relatively new to GS though I have been riding motorcycles for some time. Any help with my issue would be greatly appreciated.

The Bike:
1982 GS1100GL (shaft drive)
Version sold in the US (headlight always on)
~25,000 miles

The Problem:
I was riding the other day and the electronics and motor died (gauge lights went out and motor stopped running). I rolled to the side of the road and immediately checked fuses. The main fuse (15 amp) had blown. With the key in the OFF position, I went to put in a new fuse right then and it blew as soon as both blades made contact.

I knew there was a bigger problem at this point. To get home, I put a thick piece of wire in place of the fuse. The bike started and ran fine for the 10 min. ride home. When I got home I took out the wire and disconnected the battery.

I figured there was a ground fault somewhere. I reviewed the wiring diagram for the bike and went to work with my multimeter. With the negative battery lead disconnected, the main fuse out, and the bike off I found that both sockets for the main fuse connect to ground. Under the same conditions, the positive lead to the batter connects to ground. This seems like a major problem. The short has to be before the ignition switch because the fuse blows with the bike off. The starter and solenoid function fine. The harness under the tank seems to be in great shape. I'm not sure what to start spending time on to find answers.

Thanks

[posplayr]

Hello, I am new to this forum and relatively new to GS though I have been riding motorcycles for some time. Any help with my issue would be greatly appreciated.

The Bike:
1982 GS1100GL (shaft drive)
Version sold in the US (headlight always on)
~25,000 miles

The Problem:
I was riding the other day and the electronics and motor died (gauge lights went out and motor stopped running). I rolled to the side of the road and immediately checked fuses. The main fuse (15 amp) had blown. With the key in the OFF position, I went to put in a new fuse right then and it blew as soon as both blades made contact.

I knew there was a bigger problem at this point. To get home, I put a thick piece of wire in place of the fuse. The bike started and ran fine for the 10 min. ride home. When I got home I took out the wire and disconnected the battery.

I figured there was a ground fault somewhere. I reviewed the wiring diagram for the bike and went to work with my multimeter. With the negative battery lead disconnected, the main fuse out, and the bike off I found that both sockets for the main fuse connect to ground. Under the same conditions, the positive lead to the batter connects to ground. This seems like a major problem. The short has to be before the ignition switch because the fuse blows with the bike off. The starter and solenoid function fine. The harness under the tank seems to be in great shape. I'm not sure what to start spending time on to find answers.

Thanks

Check your fuse box to see if it has been getting hot. There is a tendency for some fuse boxes that have internal wire crimps to develop corrosion and run hot as the current flows through them. Depending upon how the plastic melts you could be always on or have a short. Regardless of whether that is the problem when you inspect use some navel jelly to etch the copper (inside the crimps) and flow some solder into the crimps to insure conductivity stay high.

See subject fuse box example below after etch and soldering

[tom203]

Disconnect your R/R (rectifier /regulator) and put in new 15 amp fuse and see what happens. A faulty R/R will cause this type of problem.
What kind of R/R do you have??

[OldVet66]

Welcome to the forum. All the wiring harness connections, plugs, switches and grounds need to be gone through, cleaned, dielectric grease applied and replaced where they have been burnt (usually the stator plug or bullet connectors depending on your model). Any, or usually a combination of these can cause your problem, but if it really was a short, your solid fuse would show you right away with a spectacular smoke test. This is a good site for replacement connectors and the proper crimping tools: http://www.vintageconnections.com/

[posplayr]

Disconnect your R/R (rectifier /regulator) and put in new 15 amp fuse and see what happens. A faulty R/R will cause this type of problem.
What kind of R/R do you have??

Tom, I reread his post and once he disconnects the main fuse (between R/R(+) and battery(+)???)
and has the ignition off then the R/R(+) should be isolated from the entire electrical even if an SCR has shorted to ground.

The apparent fact that both sides of the main fuse (including the battery +) are are shorted to ground leads me to something in the fuse box unless there is some other physical damage to the harness.

[OldVet66]

It doesn't seem to make a lot of sense that you could have driven home With a solid fuse and not have caused massive damage that you can't easily find. A dead short doesn't usually play that way. Are you sure you are not reading ground through another circuit?

[tom203]

Tom, I reread his post and once he disconnects the main fuse (between R/R(+) and battery(+)???)
and has the ignition off then the R/R(+) should be isolated from the entire electrical even if an SCR has shorted to ground.

The apparent fact that both sides of the main fuse (including the battery +) are are shorted to ground leads me to something in the fuse box unless there is some other physical damage to the harness.

I agree entirely, but I figured his description of his testing might be in error. The R/R is quick and easy to eliminate from a potential short problem before you move on to fun stuff.

[posplayr]

It doesn't seem to make a lot of sense that you could have driven home With a solid fuse and not have caused massive damage that you can't easily find. A dead short doesn't usually play that way. Are you sure you are not reading ground through another circuit?

Playing with fire on that one. Was expecting to read "....after insertion of crow bar, got home to see a ball of melted wire and gooo... what should I do"

[DanTheMan]

I've had a short in the ignition switch wiring on my 850 do the same thing, however, when it finally fried completely, the bike wouldn't shut off.

[Steve]

I don't know what to say about "both blades of the fuse are apparently connected to ground".

First of all, not sure the '82 1100 fusebox had blades, but I could be mistaken.
I know that our '82 850 and 650 both had glass fuses, but that does not mean that the 1100 had them.
EDIT: just looked at a parts fiche, the 1100GL did have blade fuses.
It is not uncommon for features to start at the top and filter down through the rest of the line over the years.

Also, if the R/R was shorted, one blade could certainly show a ground, but the other one should connect to the battery, or at least the battery terminal of the starter solenoid. That side essentially (electrically) goes straight to the battery with no fuse at all, so it should read battery voltage, not ground. Please re-check and verify.

.

[Paul]

I don't know what to say about "both blades of the fuse are apparently connected to ground".

First of all, not sure the '82 1100 fusebox had blades, but I could be mistaken.
I know that our '82 850 and 650 both had glass fuses, but that does not mean that the 1100 had them.

.

my 82 1100GL has blades (spades)

[RustRider]

Update

First off, thank you for all of these great responses. I have not had a chance to do further testing since reading replies.

I have to say, I was fully expected something to catch fire when I ran the bike home with a wire instead of a main fuse. I was desperate to make it home and anticipated obvious damage as a result. I can't find any signs of melted plastic or insulation on any of the harnesses, connectors, or around the R/R. I should also note that I am equipped with a very poor quality multimeter at the time.

I bought a bunch of 15 amp fuses anticipating some trial and error. At one point I had the bike off (key out), battery connected, and fuse in. The fuse must have been on the upper end of its tolerance because it didn't blow. However, it did get very hot. The bike was only in this configuration for moments.

I hope this provides some useful info. Once again, I thank you for your insightful replies.

[OldVet66]

Clean up all the harness connections, plugs, switches and grounds before you start troubleshooting. Saves a lot of tail chasing later. Accumulated high contact resistances can blow fuses and not melt down the system when it is over fused. Then your troubleshooting results will be accurate.

[RustRider]

Update

I was very busy this weekend so didn't get much time to troubleshoot. I did one very simple test though. With the main fuse out, I hooked up the batter and disconnected the R/R. Then I put a 15A main fuse in. The fuse did not blow or get hot. Am I correct to ascertain that this means the short is in the R/R and not any of the harnesses?

I read the Stator Papers but still don't really know how to simply test if the R/R has a short. I don't have a meter that can test diodes.

Any thoughts?

[posplayr]

I was very busy this weekend so didn't get much time to troubleshoot. I did one very simple test though. With the main fuse out, I hooked up the batter and disconnected the R/R. Then I put a 15A main fuse in. The fuse did not blow or get hot. Am I correct to ascertain that this means the short is in the R/R and not any of the harnesses?

I read the Stator Papers but still don't really know how to simply test if the R/R has a short. I don't have a meter that can test diodes.

Any thoughts?

In the diode tests you are basically trying to see if the diodes are there to conduct in one direction and block flow in the other direction. You can test this with an Ohm meter by testing in one direction for a low impedance an OL in the opposite direction.

If one of your's is shorted it will have low impedance in both directions.