TOPIC:

Pardon the remedial questions but I believe I've misdiagnosed several electrical problems because I don't know the answers.

When troubleshooting wiring:

1. When a reading calls for 'battery voltage' that means it should show what your battery is currently at. Is that correct?

For Example: I hooked up my multimeter directly to the battery and it showed 11.99 Volts. When I took a measurement further down the line it only showed about 8 Volts, thats a problem right?

2. When a reading calls for 0 Ohms, how close to zero are we talking? '000.0' only or is '000.5' also considered 0 Ohms for troubleshooting purposes?

3. Is a short/open either all or nothing or can they cause a power 'leak'?

For example: Could the fact that there is less than full battery voltage somewhere be due to a partial short or partial open?

4. When a reading calls for 0 Volts, does that mean if you are getting a reading of milli volts (mV), that you have a potential problem?

5. When looking at a wiring diagram, is there a way to tell which wire(s) coming out of a connector are positive, negative, or switched positive?

6. Do you have any tips for reading wiring diagrams? Things that maybe you didn't know when you were first starting that might help?

Feel free to add to the questions. Thanks for any and all help.

Little B wrote:

Pardon the remedial questions but I believe I've misdiagnosed several electrical problems because I don't know the answers.

When troubleshooting wiring:

1. When a reading calls for 'battery voltage' that means it should show what your battery is currently at. Is that correct?

For Example: I hooked up my multimeter directly to the battery and it showed 11.99 Volts. When I took a measurement further down the line it only showed about 8 Volts, thats a problem right?

2. When a reading calls for 0 Ohms, how close to zero are we talking? '000.0' only or is '000.5' also considered 0 Ohms for troubleshooting purposes?

3. Is a short/open either all or nothing or can they cause a power 'leak'?

For example: Could the fact that there is less than full battery voltage somewhere be due to a partial short or partial open?

4. When a reading calls for 0 Volts, does that mean if you are getting a reading of milli volts (mV), that you have a potential problem?

5. When looking at a wiring diagram, is there a way to tell which wire(s) coming out of a connector are positive, negative, or switched positive?

6. Do you have any tips for reading wiring diagrams? Things that maybe you didn't know when you were first starting that might help?

Feel free to add to the questions. Thanks for any and all help.

lets see how many of these i can guess #1-id say yes #2-zero means zero to me,but it also depends on how accurate your meter is.ive got a digital voltage/amp meter so i dont have to think too hard! #3-could be yes.a dead short will be right to ground ,but you can also have a bare spot in a wire that touches just enough to drain a battery but isnt grounded well enough to blow a circuit.#4-once again depends on how accurate your meter is,when in doubt double check on something you know is dead#5-normally ground wires are black,sometimes they will have a tracer on them,which is ass backwards from regulat a/c wiring where black is generally power! just look at the diagram,power normally originates at base of the arrow on the switch #6-there are lots of extra wires in stock harnesses that go no place,just follow through them and you will find which ones you need and dont need.good luck,happy wrenching!

Little B wrote:

1. When a reading calls for 'battery voltage' that means it should show what your battery is currently at. Is that correct?

For Example: I hooked up my multimeter directly to the battery and it showed 11.99 Volts. When I took a measurement further down the line it only showed about 8 Volts, thats a problem right?

Normally if a reading calls for battery voltage, that means the same voltage as on the positive battery terminal relative to the ground terminal. You should use the same ground point when comparing, and preferably the actual negative terminal on the battery. You can use other points as the reference ground, but the battery terminal is preferred for most applications (but not all).
If the point "further down the line" is only seperated by wire, then yes, there is a bad connection somewhere in that wire. A small drop of maybe .5v may be normal depending on how much current that wire is carrying and how long the distance is.



Little B wrote:

2. When a reading calls for 0 Ohms, how close to zero are we talking? '000.0' only or is '000.5' also considered 0 Ohms for troubleshooting purposes?

Most meters will only read down to .1 to .2 ohms or so. Those could be considered zero for general applications. But some applications, like measuring a starter motor winding, or alternator winding can be misleading since their values are so low to begin with. In those cases, it's possible that .8 ohms is good, but .4 ohms is bad. What if the meter is off by .2 ohms? It gets tricky.


Little B wrote:

3. Is a short/open either all or nothing or can they cause a power 'leak'?

For example: Could the fact that there is less than full battery voltage somewhere be due to a partial short or partial open?

Well, that dilemma is caused by different uses of the terminology and different definitions of the terms. The most common use of the term "short" is when two conductors come in contact with each other such that the resistance from one to the other is close to zero, and their voltages become the same. A "partial short" is the result of a short where the contact point cannot support the current flowing through the point. This means the metal heats up, the resistance increases and the voltages on the two pieces no longer is the same. A partial short behaves much like a light bulb. If the current is low, it's resistance is very low and the voltage drop will be minimal. If the current is very high, it will get hot and the resistance goes up. It can potentially self limit the current. What was initially a short can end up as a "power leak". I've seen this where a fuse may intially blow, but as the short burns and goes up in resistance, the next fuse may only glow. This usually only happens with "slow-blow" fuses (which are not really used in vehicles).




Little B wrote:

4. When a reading calls for 0 Volts, does that mean if you are getting a reading of milli volts (mV), that you have a potential problem?

This depends on what you are measuring. Typically, though, on a bike, a few millivolts is considered 0 volts.




Little B wrote:

5. When looking at a wiring diagram, is there a way to tell which wire(s) coming out of a connector are positive, negative, or switched positive?

Yes, but only if you understand the circuit. If you are asking if there is some sort of code on the diagram that shows it explicitly, then no.




Little B wrote:

6. Do you have any tips for reading wiring diagrams? Things that maybe you didn't know when you were first starting that might help?

Feel free to add to the questions. Thanks for any and all help.

The best way to be able to read diagrams is to start making your own diagrams. Start making small diagrams of simple battery/light-bulb circuits. Start experimenting with switching and relay circuits and draw them out on paper. When you draw your circuits you will see the type of problems you have to overcome to make the diagram clear. Then you will realize the guys that make the bike diagrams had to overcome the same problems and you'll undestand why they did what they did.

I guess the first thing is to realize that wiring diagrams are different from schematics. A schematic usually only shows electrical connections. Diagrams tend to show the physical layout of the wires and components. Generally, we use a hybrid of the two on any given bike diagram. Schematics are much clearer when trying to understand the electrical function. Wiring diagrams are much better at letting you know where the parts are located and how the connectors are organized.

Unfortunately, I don't feel as though this has been all that helpful to you because most of your questions are answered with "well, it depends". I guess, like anything else, experience is the key. Sometimes it feels like you're not making any headway, but you are, just by thinking about whatever you're working on.

That was very helpful guys, thanks a ton! I had been troubleshooting my brake/fuel indicator light problem. The first thing they always tell you to do is test the wiring.

Well, I 'tested' it and found it to be good even though it wasn't reading the proper voltage. Then I started 'testing' the fuel level switch and outage indicator. Found them both to be 'bad'. Already replaced the fuel level switch and now realize that there is power leaking to ground somewhere that is causing the light to go on at about half brightness when either of them are plugged into the circuit.

Anyway, this was helpful because it solidified some 'hunches' I was working out yesterday.