proof of ground function when the ground cant be viewed or touched with a dvm probe

[yamtom]

I hate to even bring this up here, since, I am stumped regarding checking a ground on ,,, well lets say a brand H bike. This bike has grounds that I cant reach , take off and clean, etc, except with many hours of additional labor to move everything around. I just need to know, is there a way, that I can prove with a dvm,,,,ohmeter,,,, that that ground is functioning. I have the manuals both oem and chilton, that show all the grounds, but they are buried so deep, that my local dealer must be planning his next boat purchase based on knowing that some day these things are going to be questioned. I think someone on this list is a genius with electrics , if so, can you refer me to him. Ive still got my yammis, but havnt had much trouble with them.

[IanDMacDonald]

Well, grounds are an A to B means of discharge of electricity, and a constant refetence point. So, if you have access to one end of the ground, you should see continuity back to the frame at any point. Having access to whatever device, or object that is being grounded, and traced back to the negative side of the battery will show a positive sign of a good ground. I'm not sure your question is very clear though.

[CaptonZap]

Here is a little work around.
A ground wire has two ends. Usually, one end is easier to get to than the other. Take the easiest end off, and measure the reistance from that end to the engine case or battery negative terminal. Remember Steve's caution about not all meters reading zero when the leads are shorted. Take that reading as a base figure and measure the resistance. It should be close to that, and hopefully the same as the shorted lead reading.
Do all the ground straps you can, and put the loose ends back to their spots. Ones that are in positions that are subjected to road spray are most likely to corrode, so the more of them you can clean, the better. The act of taking the terminal off and putting it back on provides a new clean path for the electrons. Even just loosening the fastener enough to work the terminal back and forth a little will, most times, restore the path, as the lock washer cuts in to fresh metal and the relative motion scrapes through the oxide between the parts. It is not as good as a thorough cleaning, but it is better than nothing.

And be thankful you don't have to make your living working on Brand H.


CZ

[TopCatGr58]

Hey Tom,

Part of the problem of using an ohmeter to test the ground is that the ohmeter only puts a very small amount of current thru the connection. With things like the Starter Motor, headlight, etc. you have much higher current levels that can cause problems IF the connection isn't really clean and have enough contact area to handle the current flow...which then leads to overheating, as well as possibly damage to the device...starter motor or such. So.....hate to say it, but if you're concerned about the integrity of the grounds, then you'll just have to invest some time to be able to access the connections, take them apart, inspect, clean plenty of contact surface area, and then reconnect...THEN apply dielectric grease around the fitting to help seal it/them to prevent further corrosion.

I actually use a copper impregnated grease that promotes continiuty of a connection.....I only use it on the large single contact points, like the frame grounds and the large power connections....not in a multi-pin connector.

T.C.

[yamtom]

thanks you guys

I knew there were more knowledgeable mech s here, than over on H list. Within an evening, youve provided more valuable insight than is present there. Thanks again.

[crazy steve]

I'll expand on this.....

As both CZ and TC said, reading for resistance only may not tell the whole story; the low current used by a meter may read fine on a 'dead' circuit but increase the current when the circuit is 'live' and the connection can go away. The values in ohms can be less than the meter is capable of reading accurately in some cases. To check a 'live' circuit, access the ground wire wherever you can with the circuit in operation and read voltage from there back to the battery ground post. You should see a voltage of about .2-.3 volts if the connection is good (representing voltage 'lost' at connections), .5 volt is marginal but may be 'acceptable', anything above that and you have a poor connection somewhere. If all the connections were 'perfect', you'll read zero volts but you'll never see that.