So I fried a wire the other day

[Guest]

I've spent all summer bringing back my 81 1100e. Near as I can tell, it was parked since 2001, and I'd say much of that was uncovered outdoors. It was a sad site, with rust just about everywhere. I started the resurection with a new battery and quickly found several blown lightbulbs plus the starter button didn't work. I managed to repair the starter button and cleaned most every other electrical contact with DeOxit. Then I cleaned the carbs, adjusted the valves, and got the engine running. All electrial appeared to be sorted, so I turned my focus to making the rest of the bike road worthy and to remove all body parts for a complete paint job. This included removing any zip ties so I could pull wiring out of the way and mask for frame touchup

I finally started putting things back together this week, and when I got to connecting the battery, something very strange happened. Of course I started with the negative side connecting the main black cable as well as a small black wire that runs from one of the rectifier mounting screws. I had done this several times before. Then, as soon as I touched the positive cable to the battery post, that small black wire went up in smoke in about 1 second. It became an open circuit faster than I could lift the postive wire back off the battery, which fortunately didn't blow up in my face. The battery then needed several hours on the Battery Tender, but it seems to hold a charge just fine now.

So, obviously I had a dead short across the battery somehow, and that short is now gone. That small wire was just the weakest link, and it opened at the same time I was disconnecting the positive, but it was not the short. That mounting screw for the recifier is at ground potential and it's connected to the black wire form the rectifier. I can re-install the battery, minus that small wire to the rectifier, turn on the key, but nothing works except the neutral light and the oil light - no headlight, taillight, blinkers, and no starter, although the starter does work if I short across the solenoid. All fuses are fine, and I have checked and rechecked every wire and connection. I find no evidence of anything being frayed or overheated, and I'm quite certain everything is connected properly. I'm no stranger to electrical troubleshooting and using meters, so I'm using the wiring diagram and checking everything that's accesible, but I'm at a loss so far. What do think happened? See photo and note what's left of the small black wire pointing off to the right.

 

[posplayr]

Have you ever considered reading GS Charging System Health in my signature. Pay special attention to Single Point ground. You obviously violated it and not due to a short.


I'm a glutton for punishment, Who ever told you to connect negative first? Whoever it was question anything they may have told you.

I read your post, the lack of a Single point ground may have saved you due to compounding screwups. Apparently you do not have a main fuse?

 

[Brendan W]

Where does the positive from the r/r go to ? If it goes direct to battery with no inline fuse you have no protection from a short in the r/r.
Wild guess but maybe you still have oil pressure and neutral light because they return through the big earth strap. Lights etc if coming back through frame or battery box have lost the link from the battery box to the battery negative

 

[tom203]

Oh look, a member sorta in my neighborhood!

Those mini r/r's are only good for paper weights. Disconnect it , charge battery and get back to following a decent wiring diagram to see how power flows from battery thru a main fuse, up to key switch, and back to fusebox to power the the other fuses.

this colored wiring disgram is real close to yours on critical stuff (ignition, headlight, signals) - print a few copies out to understand.

http://members.dslextreme.com/users/bikecliff/images/GS1100G_1982_wiring.jpg

 

[Guest]

I appreciate these quick and thoughtful replies. You?ve given me plenty of thoughts and clues. I?ve now read the GS Charging System health and paid particular attention to Single Point Ground, and I?ve tried to read / skim at least a fraction of the volumes Posplayr has written on this subject. Boy, am I glad we have you around. I have definitely violated the SPG rules. In fact, I found my harness ground unconnected (!), and I assume it was originally connected to a solenoid mounting bolt? Could this have been my whole problem? I?m thinking it also explains why the lights and starting circuit don?t work, especially since Brendan W guessed that the oil and neutral lights still work because they return through the big ground strap. I?m away from the bike for a few days, otherwise I would know the answers by now. Also, I repainted my badly rusted battery box and touched up the frame. Is the battery box supposed to be grounded to the frame somehow other than through the mounting bolts? In other words, should I be stripping some paint off?
Posplayr, I can?t see the photo of the GS750X showing the #1, 2, 3, & 4 points of the SPG. I?m wondering about #2. Where do you ground to the frame? Can you post that photo here?

 

[Brendan W]

There are usually two earth wires in that general area. One earthing the harness to the frame at the top of the airbox and another to the battery box. Most likely it earths the battery box.
Personally I wouldn't rely on frame or battery box to serve as a current return. Grind paint today, rust tomorrow.
My system collects the two harness earths mentioned above and the r/r ground wire at one of the relay mounting screws.It's a new screw slightly longer than before and becomes a post for the earths to collect at. From there a thickish wire goes to the battery negative.
I don't believe that missing a harness earth would fry the r/r wire. You may have a dead short in it.

 

[posplayr]

Brendan,
The charging currents out of R/R(+) have to return to R/R(-). They do not return to the battery unless the battery is the source which at anything about 12.8V the battery is NOT sourcing. So in plain terms if the R/R(+) is above 12.8V then all charging currents out of R/R(+) are coming back to R/R(-) even the battery charging current return. You do not need a thick wire from the "ground collection point (i.e SPG) to the battery, although it will not hurt anything. What you need more importantly is a heavy wire from the SPG to the R/R(-) because that is the wire carrying ALL of the charging current.

If the R/R where to develop an internal short between R/R(+) and the R/R(-) then that little B/W wire would have to carry all the current. If it has bad/dirty crimps it will get even hotter.

I have posted a picture of both B/W ring lugs being melted of any insulation but nothing was wrong with any of the electronics component on the bike. How does this happen?

 

[Brendan W]

I have posted a picture of both B/W ring lugs being melted of any insulation but nothing was wrong with any of the electronics component on the bike. How does this happen?

My set up is almost identical except I have ring lugs #1 & #2 together at the solenoid. Would I be better adding another earth wire from the spg to the frame or taking one of the lugs back to say the airbox mount.
Looking at the melted wire I reckon one or both were at the battery negative post and that second red wire at the positive is the r/r supply. The r/r ground is probably at the r/r mount screw. How am I doing ?

 

[posplayr]

My set up is almost identical except I have ring lugs #1 & #2 together at the solenoid. Would I be better adding another earth wire from the spg to the frame or taking one of the lugs back to say the airbox mount.
Looking at the melted wire I reckon one or both were at the battery negative post and that second red wire at the positive is the r/r supply. The r/r ground is probably at the r/r mount screw. How am I doing ?

Both wires were in the stock location, one grounding the battery box to the harness and the other grounding the side plate to the harness. Both as per OEM schematics.

 

[Brendan W]

Both wires were in the stock location, one grounding the battery box to the harness and the other grounding the side plate to the harness. Both as per OEM schematics.

OK. I've cheated and used the search function. That answers that.
'Testament to circuitous grounding strategy' and ' take pressure off those little wires'

 

[Guest]

It's fixed now! That unconnected B/W wire from the harness needed to go to the battery box mount. Now all grounds are connected properly, and everything works as it should. I must have shorted the positive from the battery directly to the frame when trying to connect it, which I now know never to do again. That small wire from the R/R to the battery must have been the shortest path. I'm lucky it went up in smoke before the battery blew up in my face. Lesson learned.
Thanks guys!

 

[posplayr]

It's fixed now! That unconnected B/W wire from the harness needed to go to the battery box mount. Now all grounds are connected properly, and everything works as it should. I must have shorted the positive from the battery directly to the frame when trying to connect it, which I now know never to do again. That small wire from the R/R to the battery must have been the shortest path. I'm lucky it went up in smoke before the battery blew up in my face. Lesson learned.
Thanks guys!

Good you have it working.

For your own sake, always remember to remove the ground first and restore it last. That is because you can not short anything till the ground is attached.

Doing the opposite (remove positive first) makes you very vulnerable to arching across the top of the battery.