basic electrical questions

[LarryA_Texas]

I'm working on a GS650 and have a basic wiring problem. So this question is directed to any DC genius that might help me understand what's happening.

The stock harness was butchered by a PO but I believe it was functioning.

After some work on the air box (mountings for the R/R, start solenoid, Ignitor box, etc were affected) we found that the START SOLENOID no longer worked. I put a tester on it and found 12 volts on outer case of the solenoid. This was tested by putting the red lead of the tester on the solenoid and black to ground (engine). In fact the entire metal air box assembly and all parts connected to it had voltage.

This bike has a metal box holding the filter that connects to plastic.

So I grounded the box to the frame with wire and...SMOKED the wire. I mean it started to melt. I dug through the wires and tried to find a place where a hot wire was tied into the ground wires and can't find any problem like that so I have reached the conclusion that the black/white wires were just not properly grounded.

I tested this theory on another bike with a multimeter. I put the red on a disconnected ground wire and the black to frame and found, as expected, ZERO volts. Doing the same thing on the 650 nets me a positive .03 to .09 volts. This is checking from a black/white wire to the frame. These black/white wires are connected to each other at several points in the harness.

So here is the question: Is it normal to have some residual voltage bleed through a properly grounded system? If not, that voltage could be leaking from the ignitor box...is this common?

After adding extra ground wires at several key spots the bike started without melting any wires. Would you think I've solved the problem or just masked it? There still is a little bit of voltage showing in any ground wire I disconnect and test. Should I keep looking for that elusive ZERO volts in the ground system?

Sorry this is so long...it's got me kinda stumped. If you got this far thanks for reading it all.

 

[posplayr]

I would say you have a short. I would not add additional ground straps as you are just going top smoke something else or at least run your battery down.

Sounds like a ground is connected to hot some where.

Not sure which is the best approach to find the short except by a process of elimination. Start removing connections and components till the short goes away. Either test with a volt or ohm meter. Since you see your air box ground is hot keep disconnecting stuff till than voltage drops.

 

[argonsagas]

I would say you have a short. I would not add additional ground straps as you are just going top smoke something else or at least run your battery down.

Sounds like a ground is connected to hot some where.

Not sure which is the best approach to find the short except by a process of elimination. Start removing connections and components till the short goes away. Either test with a volt or ohm meter. Since you see your air box ground is hot keep disconnecting stuff till that voltage drops.

Agree with all of that. You said there is "residual" voltage, and there should be none.

 

[Steve]

One quick way to start your troubleshooting is to pull the top three fuses in the fuse box. Use your voltmeter across the fuse holders, see which one shows voltage. This would at least limit your search to just one third of the wiring on the bike.

The top fuse feeds the headlight, tail light and instrument lights.
The second fuse feeds signals, which include turn signals, brake lights and horn.
The third fuse feeds the ignition system.

That should at least get you started.

.

 

[LarryA_Texas]

One quick way to start your troubleshooting is to pull the top three fuses in the fuse box. Use your voltmeter across the fuse holders, see which one shows voltage. This would at least limit your search to just one third of the wiring on the bike.

The top fuse feeds the headlight, tail light and instrument lights.
The second fuse feeds signals, which include turn signals, brake lights and horn.
The third fuse feeds the ignition system.

That should at least get you started.

.

Kind of a funny thing about that...

I did that yesterday and my .03 volts stays on the meter with ANY ONE OF THE THREE fuses connected. The only way it goes away completely is if I pull the bottom fuse which, of course, kills the system. With any one of the other three connected it shows a tiny little bit of voltage.

 

[Steve]

Well, that still gives you an idea where to look. Look at a wiring diagram, you will see that the only things that are connected to the main fuse (your last fuse) are the ignition key and the r/r. Try disconnecting the r/r to see if your voltage finally drops to zero. If it does, your problem is your r/r.

.

 

[posplayr]

Kind of a funny thing about that...

I did that yesterday and my .03 volts stays on the meter with ANY ONE OF THE THREE fuses connected. The only way it goes away completely is if I pull the bottom fuse which, of course, kills the system. With any one of the other three connected it shows a tiny little bit of voltage.

If you are smoking wires you are looking for something closer to 12V or what ever the potential is between your battery and ground.

0.030 volts is very low. When I said sounds like a short it was not because of 30 mvolts. It is because you wired a wire from frame to a supposed ground and you smoked a wire. That would more than likey require full battery potential to do that.

Go back to measuring voltage (relative to the battery negative post ) where you think you have ground and should be able to run a ground strap. You are looking for 12V not 0.03V

 

[LarryA_Texas]

update

update

I know electrical problems can get very complicated. Thanks to anyone that is reading this.

In this harness all the black/white wires have been connected to each other to form a more or less 'common' ground. Those wires are then connected at several points to the frame.

It was when they were ALL disconnected from the frame that it melted a ground strap that was just a thin wire and two alligator clips.

When they are all connected to the frame that is not the case. But if I connect the meter to one disconnected black/white wire (any one) I do get some voltage....03 to .09 volts. The bike runs and everything seems to be working except that I'm still getting voltage at the ground.

What I know so far; forget this electrical system, just basic DC wiring...If you want to connect a load (like a light) to a battery you have to have 4 things. Battery; positive wire; light; negative wire. If you remove the negative wire from the battery and connect it to a voltmeter , then connect the voltmeter to the battery you will get 12 volts on the meter. There isn't enough current to illuminate the light, but the voltage will show up on the meter. Having done that, if you now touch the negative from the light to the battery's negative terminal the light will illuminate but at the same time the voltage on the meter drops to zero. The current is flowing through the path of least resistance.

So, all the load current on my 650 should be flowing through the negative wires (Black/white) to ground on the frame. But for some reason a little trickle of voltage (.03 volts) is still showing up on the voltmeter.

By the way...that .03 volts will increase to .075 if I connect the headlight...with additional current being used to light the light and flow into the ground wires.

So, I think it would be logical to assume that somewhere a ground connection is bad and the bike isn't being properly grounded. The problem is that I've jumpered all over the bike and can't make the voltage drop at all by adding ground straps to any part of the bike.

I have also checked the main fuse panel, the igniter box, and the R/R unit individually by removing them from the bike and none of those changes had any affect.

So the first question is still out there.

Is it common to find a little bit of voltage on a ground wire?
Is this very strange and really needs to be fixed?
or
Do I just patch it up and call it good since everything works?

By the way...when it's running this bike makes a good 14.2 volts. The highest voltage to the battery of any charging system I've got. Most are around 13.

 

[posplayr]

I have discovered the problem :-\\\

I know electrical problems can get very complicated. Thanks to anyone that is reading this.

It was when they were ALL disconnected from the frame that it melted a ground strap that was just a thin wire and two alligator clips.

.

Reconnect all of your stock grounds; read this if you want to understand GS grounds and charging systems.

http://www.thegsresources.com/_forum/showthread.php?t=139115

I would do the folllowing:

1.) add a short a wire as possible from R/R(-) to a frame ground
2.) add a wire from the R/R (-) to the battery negative terminal.

I prefer to do this by creating a single point ground at the R/R mounting bolt and dasiy chain from there.

The test using the modified stator pages. from here.

http://www.thegsresources.com/_forum/showthread.php?t=143019

 

[Pete Logan]

Am I right in thinking that the engines are rubber mounted, so to do electrical tests you have to ground the multimeter negative to the frame, or preferably direct to the battery negative ?

 

[mighty13d]

Am I right in thinking that the engines are rubber mounted, so to do electrical tests you have to ground the multimeter negative to the frame, or preferably direct to the battery negative ?

The engines are not rubber mounted so you don't need to. It is always a good idea to ground to a nice clean piece of frame and the battery negative is always the best though.

 

[Pete Logan]

The engines are not rubber mounted so you don't need to. It is always a good idea to ground to a nice clean piece of frame and the battery negative is always the best though.

I stand corrected. Old age brain fart

 

[posplayr]

The engines are not rubber mounted so you don't need to. It is always a good idea to ground to a nice clean piece of frame and the battery negative is always the best though.

Theoretically and practically the lowest DC voltage on the GS is the R/R (-) wire. All stator return currents return to this point.

It is not well understood that all currents that the stator generates must return to the stator. So all current that is sourced at the R/R(+) is returned (sunk) to R/R(-). This is contrary to common GS charging folklore that incorrectly suggests that all currents return to the battery (-). The only currents that return to the Battery (-) are those that are produced at the battery (+) namely any starter currents.

So with respect to what should be ground in a GS; it is the R/R(-) as it is the lowest DC voltage during normal charging. Therefore paths need to be provided from both the battery (-) to the R/R(-) to pickup battery charging currents and from the frame to the R/R (-) to allow all frame return ground to get back to the R/R.

Of course there is a big starter ground strap between battery (-) to Engine and the engine is bolted to the frame. The way Suzuki designed the system, charging currents returning from the battery had to flow from the battery (-) to
ground strap to engine, then through mounting bolts to the frame from the frame ground to one of the black/white ring lugs in the harness then back down the other black/white ring lug to the side plate where the R/R 's are typically mounted. That probably worked well when the bikes were new, but with years of grease and corrosion that path develops resistance and seems to cause problems. I have personally experienced and see more than one person port that they had smoked ground wires.

 

[pdqford]

In this harness all the black/white wires have been connected to each other to form a more or less 'common' ground. Those wires are then connected at several points to the frame.

And the frome is connected to the battery (-) with a heavier cable. So all these black/white ground wires feed the ground portion of their respective circuits to the frame. The frame is like a really heavy wire as it carries the sum of all the circuit grounds to the ground cable which in turn connects to the battery (-).

It was when they were ALL disconnected from the frame that it melted a ground strap that was just a thin wire and two alligator clips.

Larry, to what was each end of this thin wire with the two alligator clips connected when it melted?

When they are all connected to the frame that is not the case. But if I connect the meter to one disconnected black/white wire (any one) I do get some voltage....03 to .09 volts.

Just to be sure we all understand, you connected the + lead of the DMM to one black/white wire that is disconnected from the frame (while all other black/white wires remain connected to the frame), and you place the - lead of the DMM (set to read DC voltage) on the battery - post?

If that's what you did, I'd say you are measuring the voltage drop accross the ground side of the bike from that black/white wire, through the frame, through the battery ground cable and connections to the - battery post. If you get anything less that 0.2 Volts DC, you got good grounds.

 

[posplayr]

And the frome is connected to the battery (-) with a heavier cable. So all these black/white ground wires feed the ground portion of their respective circuits to the frame. The frame is like a really heavy wire as it carries the sum of all the circuit grounds to the ground cable which in turn connects to the battery (-).


Larry, to what was each end of this thin wire with the two alligator clips connected when it melted?



Just to be sure we all understand, you connected the + lead of the DMM to one black/white wire that is disconnected from the frame (while all other black/white wires remain connected to the frame), and you place the - lead of the DMM (set to read DC voltage) on the battery - post?

If that's what you did, I'd say you are measuring the voltage drop accross the ground side of the bike from that black/white wire, through the frame, through the battery ground cable and connections to the - battery post. If you get anything less that 0.2 Volts DC, you got good grounds.

It happened the same way this happens; both wires with ring lugs used to be black/white harness grounds. This happens as per the description I provided. The R/R (-) needs to be solidly attached to frame with as short of a lead as practical.

 

[LarryA_Texas]

another update

another update

Thanks to all for the advice and technical information. I tried the strap from the stator (-) to the frame (three inch wire), and from that attach point to the battery neg post.

At the same time I tested the voltage by connecting a DMM + wire to the ground wires and the DMM neg to either the battery or the engine. The ground wire I used was firmly connected to all other ground wires within the harness and is an extra because this system used one black/white to the fuel tank probe and my gas tank is for a different year model with no gas gage.

There is still voltage on the ground wire. It's slight...about .07 volts with the headlight on. It's .03 with it off. Connecting the additional ground wire to the battery drops it by about .005 volts in either case.

The bike seems happy with this little bit of voltage. I have scrubbed corrosion off of the ground wire connector loops and it had no affect.

The only reason I question it is because my other motorcycles have ZERO voltage when measured this way.

 

[pdqford]

At the same time I tested the voltage by connecting a DMM + wire to the ground wires and the DMM neg to either the battery or the engine. The ground wire I used was firmly connected to all other ground wires within the harness and is an extra because this system used one black/white to the fuel tank probe and my gas tank is for a different year model with no gas gage.

There is still voltage on the ground wire. It's slight...about .07 volts with the headlight on. It's .03 with it off. Connecting the additional ground wire to the battery drops it by about .005 volts in either case.

So if I am following correctly, with that connection your DMM is measuring the voltage drop in the ground side of the circuit. (i.e., most voltage is going through the ground wires to the battery, while only .07 volts (with the headlight on) is trying to go through the DMM). I'd say thats pretty darn good and would only be concerned if you were dropping .75 volts or more through the ground circuit.