Topic: Testing electrical components

[pmpski_1]

I've rebuilt my carbs and done other work on my bike, but I have no idea how to test some of the electrical components on it. I'm still having trouble with the bike, but I'm working through troubleshooting thanks to the archives here.

I have a multimeter and have tested the battery voltage. That is the only thing that I know how to test.  The instructions that came the meter only tell me how to turn it on and how to replace the battery. I guess people who buy these things know how to use them.

How can I test the following components? Where do I put the leads and what setting do I use on the meter?

1. Coils
2. Plug resistor caps
3. Continuity

Thanks from a total electronic newbie.

[kghost]

You want the Ohms setting to test those.

Thats the symbol shaped like a horse shoe.

Just make sure theres no power on the cicrcuit.

It would help if you posted a picture of the meter as there are about a million varietys.

Then we could walk through them one at a time.

[pmpski_1]

Yeah, I know there's a bunch out there. I got it at Home Depot, but there's not a picture of it on the website. I'll have to get a picture of it sometime this week... I don't have it with me right now.

There are a couple of Ohm settings, I guess it depends on how many ohms you're testing. There's different settings. For example, with volts they have different settings for whole numbers, hundreths, etc. ... how do I test the coil and resistor caps as far as where to put the leads on the part I'm testing?

[TwoTired]

Have you looked here?
http://www.sohc4.us/forums/index.php?topic=261.0

[computerpulse]

For the coils I would just connect a spark plug to the wires and hang them to the engine and crank it over to see if the spark plugs fire.  If each wire fires with a spark plug then you know your coil section is working.

[oldbiker]

Also remember that when testing for resistance, the first step in the test is to connect the two probes together and adjust the resistance zero setting with the adjuster knob on the front. If you don't do this the readings are incorrect.

[jbailey]

As an Electrical Tech with 25 years of experience, I can tell you this, the meters they sell at home depot or anywhere for cheap (less than $50) are OK for general use such as checking batteries or troubleshooting an electrical system.  If you are trying to read coils or other low resistance circuits you would be better off to purchase a good digital meter such as a Fluke.  You will probably not get an accurate 3 or 5 ohm reading on a cheap analog meter.  Autoranging is a great feature found on more expenive meters which chooses the correct scale for you.  You can't really make a mistake with one.  With a Fluke you can actually leave your meter on ohms and put it on a live circuit.  A cheap meter will usually just give you a puff of smoke.  Don't bother asking how I know this, just take my word for it!!

[pmpski_1]

Ahhhhh, the FAQ. I shoulda checked there ... sounds good. Only problem is that I'm a multimeter newb and I have a question. What setting do I use for continuity? Does it matter which probe (+ or -) goes to which end while checking continuity?

Also, is the continuity test just to make sure that there are no breaks in the conductor? In other words, making sure that there is a continuous path for electricity to flow?


I've done the plug to engine block test, and I have spark, but I just want to take more measurements and learn how to use this meter.

Here's a pic of the meter.

[Dennis]

With a Fluke you can actually leave your meter on ohms and put it on a live circuit. A cheap meter will usually just give you a puff of smoke. Don't bother asking how I know this, just take my word for it!!

C'mon bailey,
anyone with a little electrical experience doesn't have to ask how you know that!! LOL
We have all done it, haven't we??
Of course the fuse on my Fluke has saved me a few times also (when I left it set for amps and tried to measure volts). Sometimes I just forget to pay attention.

[TwoTired]

Continuity is just checking for an electrical connection.  The best conductor would have 0 Ohms (practicaly impossible, but you can get very close).  For your meter use the 200 ohm scale unless you are checking a diode. (more later)  Resistance ranges from near zero to infinity which is essentially open circuit or no continuity.  For circuit testing with no diodes or active component invloved (wires. connectors, resistors) probe polarity is irrelevant.

 The diode setting inserts a higher voltage into the circuit you are testing so that diodes will conduct in the forward direction. Probe polarity is important for this test, as a diode should only conduct with one polarity.

There should be a spec sheet for your meter that tells its resolution or accuracy for each setting.  Your display for the 200 ohms scale has a resolution of 1 ohm.  However, the circuit driving the display will have some measurement error (see the spec sheet) and the probes also have some resistance that should show on the display.  Further, your display may read zero if you have less than .5 ohms and may read 2 ohms when you measure 1.6 ohms.

It is unlikely your meter will be useful to measure alternator windings, as those are .35 ohms which is lower than your display resolution.