Multiple or less, which is best?

[andyoutandabout]

Peeps, here's an interesting nugget that cropped up during a recent discussion on FJ matters.
The notion of multiple grounds.
A weak ground has oft been implicated in a vast range of electrical 80s oddness.
I think I remember cures like run an independent wire from troublesome component to battery negative, so had done this with the bouncing gauges, dud self cancelling indicator black box, coils maybe etc.
However, not naming any names, but Frank said it's a bad idea to set up extra grounds as they interfere with the ether or something.
Anyway, just curious to know the group consensus
Here's a vote thingy, nope couldn't figure that out.
Yes - run earths to the battery whenever you fancy
No - don't add to the existing diagram, just make sure what is original is clean
Maybe - somethings benefit greatly from a direct earth to the battery terminal.
VOTE NOW

[Tuned forks]

Maybe

Joe

[FJmonkey]

Any place like the electrical on the top of the yoke needs a ground wire. It should already have one in the factory harness. But if that ground fails, and the path to ground goes through the steering bearings to get to the frame, it will eat the bearings up.

[Charlie-brm]

Get acquainted with a multimeter if you haven't yet.

I won't walk you through using it but to get a baseline of the meter's own "zero" Volts value, put the setting to the lowest available Volts range and touch the leads together.
Note the value. e.g. I just checked mine and the lowest range is 200mV. Shorting the leads together it displays "0.1" or sometimes "0.0" so that's my meter's zero.
Just pointing that out though it sounds obvious because some cheap meters are not going to display a perfect 0.0

Now if you want to check how good your grounding is here and there on the bike, turn on the bike's power. Keep the meter's negative lead on the battery's negative terminal and start probing your outlying ground points.
Anything indicating higher than "zero" is because the ground routing is offering resistance instead of being a perfect ground to the battery and you're reading what is "residual" voltage. Really it's a matter of what that circuit can live with to function properly, if not at peak.

If there are things up front that are collectively not getting a good ground, I would put one good new ground lead from the battery up to the frame near those things and bring them all to ground there. The wire gauge from the battery ground depends on the anticipated total load.

While the meter is out, it's a good idea to measure voltages on the positive side of things like the coils and the headlight before running off and installing the relay mods for those and not knowing what the improvement is going to be. e.g. I can tell you exactly the before and after voltages to my coils and to my headlight, which in the case of the headlight translates directly into power = brightness.

Mostly my demons with grounds were when installing sound system amps in the trunks of cars, or installing remote starters and alarms. We'd get hums which was pretty obvious to notice and to cure. But the alarms took the cake for acting up, being sensitive to voltage and current on a dozen different sensors.

[ribbert]

Peeps, here's an interesting nugget that cropped up during a recent discussion on FJ matters.
The notion of multiple grounds.

Did someone say multiple earths?



Well, there's all my earths up the front (blue arrow). That threaded lug on the frame is already there.....






.... and the ones in the middle (and now sporting at least one more).





.....and the ones up the back!

Noel

[CutterBill]

Multiple grounds can cause problems in equipment (airplanes, modern cars...) with sensitive electronics. If one ground point is at a slightly different potential than another ground point, then you get what is called a "ground loop." This can cause noise (static, humming, erratic gauge readings...) in a system.

However, in our stone-age simple bikes, multiple grounds (such as Noel showed) is not going to cause a problem. A far better solution would be to make all of the existing ground points as perfect as possible. A welded frame has purt-near zero resistance so ground wires can be attached at different points without fear.  But most people don't realize the importance of taking the ground point (frame) down to bright, shiny metal before attaching a wire. It should be absolutely perfect. But if you want to go all "belt-and-suspenders", then you can add an additional ground wire without problem.

One place where a ground wire would be especially useful would be if I had to run current thru a bolted joint... for example, I wouldn't ground a component to the rear sub-frame and rely on the bolted connection to the main frame. In that case, I would run a ground wire. Hope this helps.
Bill

[Flynt]

...but Frank said it's a bad idea to set up extra grounds as they interfere with the ether or something.

Not sure what I said exactly, but I meant grounding things to different points on the bike...  especially different pieces that are connected mechanically (bolted, clamped, etc...  not welded) will often cause the "ground loop" phenomenon.  Simple solution is to ground everything to one physical point or, at least, to one conducticve piece (like the main frame, not the bolted on subframe, lower rails, or engine for some grounds and frame for others). 

In Andy's particular case his tach was acting strangely and I suggested he might have a bad connection between his various grounds (he has the coil relay mod in place) and sent him searching...  he found a connector that was pulled loose on the relay that was working fine at low RPM, but would get funky the moment he revved the engine.  Plug the connection in firmly and GTG!

I usually start any electrical investigation with checking of grounds and battery connections...  most times a thorough investigation around these areas will reveal the issue(s) causing the ether interference.  A decent multimeter "ring out" of the system is a good first step.

Frank

[Troyskie]

Andy, GREAT thread to start.

I am a complete novice when it comes to electrics. What everyone has contributed is simple, clear and easy to follow. This is really educational to me.

A question now. Should I bridge all my earths together? From the back of the engine, to battery to the subframe/frame to the Handlebar controls? Or is that done in the harness?

Bill, the FJ electrical system to me is not stone-age, but magic! I've had a small share of issues which have been solved here or with friends. But, it is still waaaaaay more complex than simple circuits which I've impressed my kids with (they now know more than me). To those who are electrically (or logically) inclined, I bow my head.

Gareth (Mr Blackstock) has added some really elegant pearls of electrical wisdom. Are you still reading the forum?

[JPaganel]

One thing that I ran into is ignition coils grounded to the subframe.

Over time, contact between main frame and subframe can get wonky, and that gets you intermittent ignition issues. You can fix this either by grounding the subframe to the battery, or by moving grounds of everything that is grounded to it to the main grounding point on the block or battery.

[balky1]

A question pops in my mind when reading this. Is it possible to access the ground wire on the back of the motor when the motor is installed? I have no idea where that wire is....

[Pat Conlon]

Is it possible to access the ground wire on the back of the motor when the motor is installed? I have no idea where that wire is....

Yes, on my bike I had to remove the battery, battery box and splash shield.
This is a very important connection

[balky1]

Is it possible to access the ground wire on the back of the motor when the motor is installed? I have no idea where that wire is....

Yes, on my bike I had to remove the battery, battery box and splash shield.
This is a very important connection

Thanks. I already wanted to check it/clean it, but couldn't find it.

[andyoutandabout]

That was the phrase Frank; 'ground loop'. The concensus then is to ground to the engine or main frame in a few solid, clean points.
A bit of tidying goes a long way.

[ribbert]

That was the phrase Frank; 'ground loop'. The concensus then is to ground to the engine or main frame in a few solid, clean points.
A bit of tidying goes a long way.

I have added 16 additional electrical items to my system, everything, including original is earthed either through this point on the frame or direct to the battery.




All the rest of my system is original @250k, including regulator and switch gear and I've never had a problem with any of it, not that I would expect to. I did replace the rear brake light switch once and I use AGM batteries.

The "earth" point shown above is a tab on the frame with a 6mm nut already welded to it, it appears to be redundant on all the FJ's I've seen and makes a perfect ground.

Noel

[andyoutandabout]

A few rally fireside chats later and all was done with the topic of electrics.
Or so I thought....
My earth is definately dodgy, probably due to the fact I painted my frame and perhaps don't have great continuity there.
Anyway, got to looking at a wiring diagram again and tried to spot frame earths
If anyone has a relatively stock harness, can you tell me where the earths actually are?
There's the big one that goes to the back of the engine block.
There's the skinny one that connects to the coil bolt
hmmmm that's about all I can remember at he moment.....
More?