Someone might say "you can't have too many grounds", but I like to think of it more as a quality thing, not a quantity thing. A single, good quality cable of sufficient gauge size with clean & tight terminations is better than two separate but lousy and undersized corroded cables. In any case like somebody mentioned a voltage drop test doesn't lie. Don't have to guess or have sleepless nights tossing and turning, just measure with a low ranging voltmeter. It's about as simple and basic a check as it gets going back over 100 years, and will head off any potential defects or problems with ignition, charging, starting, and lighting circuits. The basic principle is based on the fact that measuring small amounts of ohms resistance in a low voltage, high current circuit is all but impossible, so the circuit is tested while energized, under load, for voltage drop. Any excess resistance is inferred by the amount of voltage drop. For example. Set your voltmeter to the lowest range. Place one probe on the battery ground post itself, right on top. Place the other probe on the starter case or mounting lug itself, a clean bare spot. Disable the ignition and crank over the starter for a few seconds. The total or cumulative voltage drop in the entire starter ground circuit will be displayed on the voltmeter (as a positive voltage) what happens is the electrons find it an easier path through the voltmeter, than they do through the corrosion in the electrical connections. The voltage drop limit for the ground circuit should not exceed 0.2 volts. If limits are exceeded it is a simple matter to incrementally move the probes closer together to find where the problem fault lays. One thing I've noticed is people will spend a lot of money bolting on high dollar parts but balk at replacing 50+ year old battery or ground cables or, they buy those really crappy universal generic part store cables in the blister pacs.
I've worked on some OT ATVs, where the ground was a heavy cable from battery negative to one of the starter bolts, and then clamped in the same connector as the heavy wire there was a small wire going to the harness for all the "low power" grounds in the system. Problem was the starter bolt liked to come loose, so no good connection between the heavy wire and the starter. Instead the ground current would go starter-engine block-frame and then to any part grounded through the harness (probably ignition coil, voltage regulator and such things) and back through the small ground wires in the harness. Instant harness BBQ. Just one example of how multiple grounds that kind of interconnect can cause expensive damages when one fails. If the starter (or the other parts located at the frame) had only been grounded through the cable and been isolated from the block etc. the current couldn't go through the small wires, so if the cable came loose that would only lead to the starter not working. I've also noticed that people don't mind buying and changing a bunch of expensive parts trying to solve electrical issues, but they don't want to spend ten dollars on a basic multimeter to actually figure out what the problem is so they can fix the one thing that causes the problems.
You have to realize many folks do not know how to use a meter, how to test, etc. what comes natural to you is voodoo to them. That’s what’s great about Internet forums. Ask questions, get some answers, ask more then get comfortable. Now if we could just get @The37Kid to wire up a on/off switch for a remote light in his car, we’d have success. Just kidding
"Parts changers". Yeah, it's a problem, I was subject to it once just like most everybody. I think maybe it is natural or something. I remember the classes we took the instructors of course always emphasized methodical troubleshooting. Maybe it is based on being impatient as a yoot, or something. Besides, that shiny new carburetor right on top will pretty much fix everything. Who needs a voltmeter?? One thing that helped me is I couldn't afford to throw parts at something, or replace components unnecessarily, economic necessity made it a requirement to find out what the actual fault was. In the .mil it meant my weekend would likely be trashed if I couldn't figure something out, aka "only two more workdays till Monday."
I have had ground faults and they are not fun. During wiring, after running 3 or 4 good grounds from the battery, frame, engine, body, dash I constantly check everything that is supposed to be grounded with a meter. If it doesn't ring out there is a ground problem at that point. Can't be too safe with grounds
Another common error, people will say things like "check the grounds" to someone who has no idea what that really means. It isn't their fault, but "they look fine" isn't electrically definitive here. Another good 'un is checking for "continuity". This is pretty much next to useless, a starter cable will have to carry 150 amperes, but even a single strand of magnet wire will show "continuity".
Not sure if this is local to Sweden or spread equally around the world, but for some reason people seem to be genetically coded to say "Kolla efter jordfel!" (Check for ground issues!) any time there's an electrical issue on a car, motorcycle or something like that. Doesn't matter what the problem is, what the symptoms are, the first suggestion is always an automatic "jordfel!", and it's also almost always the last suggestion as that seems to be the only thing in an electrical system they know the name of. Ground can be a major part of any electrical system so statistically there's a descent chance they're right, I'll give them that and that it's usually a good idea to check power & grounds, but that's about as much value as one should put to that suggestion.
Not so much when I was in automotive, but now working on forklifts and heavy equipment, I got burn on this a few times in the beginning. “ but I got continuity and almost 0 ohms resistance or I got full battery voltage here but it’s static voltage , no load “ couple hours later do a voltage drop test or open up the harness or maxi fuse and either find a fuse that exploded internally but is hanging together by a thread , or a 1 aught wires that’s been chaffed down to 2-3 bare copper threads. electrical diagnostic can be fun if you know what you are doing , or a nightmare if your not willing to learn .
[QUOTE="VANDENPLAS, post: 14347870, member: electrical diagnostic can be fun if you know what you are doing , or a nightmare if your not willing to learn .[/QUOTE] ESPECIALLY when one KNOWS he is right. But isn't! Ben
The Jalopy Journal
