Electrical woes

[erdmania]

Hi folks,

I'm having an electrical issue maybe someone can shed some light on. The bike is a 1980 (more or less) GS1000G. It goes like this: I recently got my bike back together after getting the fuel tank painted, taking care of some oil leaks, replacing the driveshaft boot, etc. Now, when I turn the key, no lights or anything. No fuses are blown. Also, I just noticed that the neg. battery terminal is HOT!. So I took out the battery to prevent catastrophe....

I'm thinking it's one of two things:
1. There's a short somewhere.
2. The battery is bad.

Can anyone confirm or deny either of these or offer any other suggestions?

Thanks
Ben

[Steve]

First, test the battery. How old is it? To test it, measure the voltage of the fully-charged battery at rest. Then use jumper wires to connect it to a headlight. Monitor the voltage for a minute or so. It will drop steadily, but it should be rather slow. If it drops quickly, you need a new battery.

Hot negative wire? First of all, make sure all your connections are correct, clean and tight. There are enough connections in there to confuse some people, and sometimes a previous owner (PO) will change things and confuse them even more.

Did you ever notice that Pi$$ed Off has the same initials? 8-[


.

[Killer2600]

Yea definitely sounds like a short, might what to check your starter relay and starter to make sure they aren't shorting out also check your regulater for a short.

[erdmania]

Thanks guys for your replies. I'm fairly certain there's some kind of short going on too. I have confirmed that the battery is OK though.

I've now observed that sometimes I can actually get lights and the engine to crank even. But other times the lights will go on, I turn the key to start and the starter relay clicks once then everything is dead again. Then it will stay dead no matter what, and that neg. post on the battery will start heating up again. Sound like a failed starter relay passing juice straight back to the battery? Is there a test I can run with the meter to tell if the starter relay is dead or not? Or could it possibly be anything else?

[erdmania]

Oh, and can a starter relay be rebuilt? Because Bike Bandit wants $50 for one. Ouch.

[tconroy]

Oh, and can a starter relay be rebuilt? Because Bike Bandit wants $50 for one. Ouch.

I think you can just buy one at the parts store for a lawn tractor that will work.

[Killer2600]

Starter Relays really aren't rebuildable, just a replace if broken item. As far as tests you can check the continuity across the poles of the starter relay and also the continuity between the battery side pole and ground. Do this with the battery disconnected. If the poles of the relay show anything less than infinite resistance the relay is shorted out, if you show anything less than infinite resistance between the battery side pole and ground you have a short that may be in the relay but that's usually rare, it'll likely be elsewhere.

[txironhead]

When the starter relay clicks once and the wire starts heating up, are you holding down the button? If your starter's seized, the solenoid is delivering major amps to a motor that won't turn and things start heating up quickly. I'd replace the solenoid (even one from an old Ford will work) and then test the starter. It may have been on its way out when you started repainting, etc.

[erdmania]

Update:

I tested continuity between the positive and negative battery wires - none. I hooked the battery back up, turned the key to on, I got lights, and the neg. battery terminal did not get hot. Then I made sure the ignition switch was in the "run" position and hit the starter. One click and everything went dead, no lights, nothing. I checked the neg. battery terminal and it was hot. I unhooked the battery and tested continuity at the positive and negative battery wires - none. Same between the starter relay poles.

I'd appreciate any more ideas anyone has....what would cause the electrical system to just drop out like that, with no apparent short?

Thanks
Ben

[mortation]

I would back pedal a bit. Was the bike working correctly before you took the tank off and messed with the boot?

I would look around where you were tinkering for any disconnected, loose, crimped, or grounded wires. Make sure the grounds are all correct, make sure the battery terminals are tight and clean. Make sure the battery has a good charge.

[SPARKSS]

Thanks guys for your replies. I'm fairly certain there's some kind of short going on too. I have confirmed that the battery is OK though.

I've now observed that sometimes I can actually get lights and the engine to crank even. But other times the lights will go on, I turn the key to start and the starter relay clicks once then everything is dead again. Then it will stay dead no matter what, and that neg. post on the battery will start heating up again. Sound like a failed starter relay passing juice straight back to the battery? Is there a test I can run with the meter to tell if the starter relay is dead or not? Or could it possibly be anything else?

The fact that your negative post heats tells you the battery is capable of producing power. THAT it heats (and not the positive?) tells me that the cable is probably loose or corroded or otherwise causing excessive resistance here.....and that a good amount of current is flowing through that bad connection (doesn't have to be a LOT of current either......see ohms law).
What could be happening is that your starter relay pulls in, connecting the starter motor (which draws a large current) and the voltage drops badly due to the connection causing the motor to not turn, maybe (or maybe NOT!) the relay to drop out.....if it hangs in or temporarily welds due to the unturning motor (current is high) then it just sits there and burns the bad connection until the battery dies.

Check the obvious. Do you have a voltmeter and are familiar with using it? If you don't, it will be a huge asset to get and become familiar with one.

[aosmith]

I'm not sure about your bike but mine has a smaller yellow wire that runs between the blinker/ hi / lo beam switch and the start button you would be shorting that to the frame mine was hidden inside the wiring pocket.
Good Luck
-Alex

[erdmania]

SPARKSS,

Are you saying maybe the neg. ground cable from the battery to the frame is loose or corroded? That's what I got from what you wrote. What you wrote makes some sense, I just want to clarify.

And does that explain why I can leave the battery disconnected for a while (i.e. overnight) then come back, reconnect it and replicate the problem?

Thanks!
Ben

[SPARKSS]

SPARKSS,

Are you saying maybe the neg. ground cable from the battery to the frame is loose or corroded? That's what I got from what you wrote. What you wrote makes some sense, I just want to clarify.

And does that explain why I can leave the battery disconnected for a while (i.e. overnight) then come back, reconnect it and replicate the problem?

Thanks!
Ben

Thats the area I'd check Ben. With a voltmeter in hand I'd try to replicate the problem......then quickly check voltage across the ground side connection (you are connected correctly aren't you?). Just in case you're unfamiliar with doing this, it'll be postive meter lead to the negative battery post and negative meter lead to engine block.....you should have very low or negligible voltage drop indicating a good connection. If you see a few volts (gasp), you've found your problem. Think of this......system loads....lights, starter, horns, ignition etc are designed to provide a certain performance at a particular voltage level (12 volts DC being one of these). The source (your battery and when running battery PLUS charging system should be able to provide the load with that voltage at whatever current the load requires. With this in mind......assuming these 2 are ok, then making sure the wiring (including switches, fuses, relays, flashers etc) is capable of transferring the current without significant voltage drop, is the next most important thing. So voltage drop testing, end-to-end, of the various parts of an effected circuit is an important part of your diagnosis. Make sense? (apololgies if you're familiar with this!)

[erdmania]

Great news!

I did the voltage test SPARKSS recommended from the neg. battery pole to the engine block and the bike started up, showing only a small decrease in voltage on the meter. I am thinking that the meter added enough of an extra ground to overcome the issue. I detached, cleaned and reattached the ground cable from battery to frame. Since that I am able to start the bike effortlessly and no more hot negative post on the battery.

So at this point SPARKSS, I'll say you were exactly right. I owe you a beverage of your choice. Thanks again, and thanks to everyone else who helped out too.