Electrical Mystery

[81g11]

Hello everyone, hopefully you can help me out i have a 1981 GS1100E. The bike has been running great all summer with the exception of a voltage regulator/rectifier. Then one day on the ride home from work the bike seemed to loose voltage the headlight dimmed the signals cut out and it barley made it home. Once i got it in the garage (still running) i put it in neutral and as soon as i let the clutch out it just died. And i don't mean just the motor the hole bike lost power it was like you disconnected the battery. I proceeded to test the battery terminals, ignition switch, and continuity between the two and it was all good, then all of a sudden it came back on but now my neutral indicator light and low oil light don't come on despite the fact that the panel and bulbs are good and so are both the sensors on the motor. i also lost my rear turn signals and brake light, not to mention the the entire check panel stays lit all the time. it did this once before in 1997 but came back shortly after i figured it was a bad battery connection and this was also on the old voltage regulator. i have checked everything they give me specs for in the service manual and sadly Im lost any info is helpfull oh and currently the motor will start right unless it completely cuts out dispite the all the probs

Thanks Brad

[don]

Hi 81g11,

I have no clue what your bike is at all, unlike the rest of these guys. But, I work as an electrical engineer on industrial equipment so my information is general in nature. You'll have to apply it to your bike from there. It may not help you at all, but the symptom you describe tells me that, in general, you have a/some wires that have chaffed through to either ground or each other. When i say to ground etc, a wire can be worn through the insulation and you can see copper but there is still enough resistance to what it is touching to not show continuity. I'm not sure if I have explained what I mean clearly or not. (I sometimes do that. But I know what I mean. lol)

I'd check the harnesses and the electrical side of your dash for visible signs of wear to start.

Hope it was helpfull.

[chef1366]

Does your dash have the picture of the bike with the idiot lights? There is a black box that controls all that jazz.
I would open the headlight bucket and check the ignition wires.

[psyguy]

i think you might need to go through all the wiring / connections and check for loose connections, chaffed wire insulation, check grounds, etc

the problem you're describing doesn't sound particular to any one component

[lucabond]

Check the ground from the battery to the motor. Remove the cable at the motor and shine up the motor mounting area and the cable end. Wouldn't hurt to add another heavy cable between the motor and battery.
Hope this helps, Good luck.

[duaneage]

Sounds like the fuse for something popped.

[81g11]

i think it has to be a short to ground like you said. i cant seem to find a wiring diagram for it, im wondering if there is something that the nutral and low oil sensor go into befor the pannel? maybe a conrtol box or circuit board? oh and yes it is that panel with all the idot lights and im not sure how to test the little circuit board in there they give me no specs on it in the manual or resistance values but all the connections behind the head light are clean.

[duaneage]

The oil light and neutral indicator are supplied with 12 volts, the bulbs light by providing a ground on the engine. Other things are usually on the same circuit, like turn signals, side stand light, and sometimes the gear indicator stuff. If none of that is working look for a fuse that opened up. Now to find out what is wrong power the bike with a battery charger (so the battery does not take a bath) and with new fuses start wiggling wires in the headlight bucket, along the frame, and other places. When the fuse goes you found your problem.

Buy at least 10 fuses, this could take a while. If it blows right away you should unplug the gauge and turn signal stuff in the headlight bucket and try again. If the fuse blows it is in the harness along the frame., If not then the problem lies in the gauge set or turn signal circuits. connect one then the other to see which.

You have to take a careful approach with these problems, and yes a diagram would help . Can anyone out there send him a diagram?

[lucabond]

Looking at a few wiring diagrams although I couldn't find 1 for your exact bike it seems the lights all share the same power line. Look at all the lights and see what wire they all share. That wire should go back to the fuse box and get its power from the key switch. I would look for power from the wire they share first at the fuse with the key on. Check both sides of the fuse for power with the key on. if there is no power at the fuse trace the wire feeding the fuse, probably orange back to the key switch. I'm thinking its the key switch. You could pull the fuse and jump power from the battery to the wire feeding the lights and see if the lights come on. That would eliminate those wires and you would have to see why there is no power getting to the fuse from the key switch. Hope this helps, Good luck

[psyguy]

i think bikecliff website has some wiring diagrams

[don_gibb6512]

I've got the wiring diagram in pdf format and I think most of the electrical section pages from the service manual. Send me a pm with your email addr. and I'll forward those on to you.

Don

[duaneage]

You could pull the fuse and jump power from the battery to the wire feeding the lights and see if the lights come on. That would eliminate those wires and you would have to see why there is no power getting to the fuse from the key switch. Hope this helps, Good luck

Good idea, however....
Get an inline fuse holder and 15 amp fuse from radio shack and use that to jumper around the fuseblock. This will protect the wiring harness in case there is a short. Failure to do so could smoke something,