Can someone teach me how to use a multimeter?
 

I am trying to troubleshoot an electrical problem on my Mercedes. I tried to post this on other site, but no reply.

I am trying to test a switch to see if it is open or close. I applied a resistance to the switch. At first, it shows "1", then it drop to about .324. Don't know what this mean? I don't have the manual to this multimeter. What does it mean when it drop to zero and if it stay the same at "1".

Is there any engineer here? This site has been so instructional for me to maintain my Porsche.

Thanks,

John

Multimeter
 

Your best bet is just to use the continuity setting. Most DM Meters will give a tone for continuity when a connection is present.
If this does not help, try your local Radio Shack Representative.

Regards, Louie

When the MM is set to test resistance a switch in the open (off) position should show no needle movement or 0 on a digital. When the switch is closed (on) the needle should pin ot the right.

One of my favorite tools for testing electrical things is a flashlight. I know, I know, but hear me out. Go buy a CHEAP plastic 1 AA type flashlight and drill a hole in the bottom and in the side. Run a couple of wire in the holes and solder them to the bottom and to the switch. Then every time you touch the wires together the light bulb will come on.

So, in your case hook up the wires to the switch and flip the switch. If the bulb comes on the switch is good, if not the switch is not good.

If anyone wants to see this set up let me know and I'll post some pics.

Good Luck!

You might want to take a look at a document called basic ammeter use or at this website. Both do a pretty good job of explaining multimeter use.

A better snapshot of the validity of an electrical connection is to test for voltage drop - the amount of system voltage being used up to push the electrons through the various parts of a circuit. Ideally, all 12 volts (source voltage) should be used up by the load (radio, motor, light bulbs, etc.); the loss in the various circuit connections should be <.1 volt or so. Much more accurate than other methods and safer for vehicles with electronic-controlled circuits (the reason troubleshooting w/a test light is no longer recommended by manufacturers).

To measure "voltage drop", switch the circuit ON, then place the voltmeter leads on each end of the section to be tested or on the device to be tested. In the case of a switch, place the voltmeter leads on each switch terminal, then close the switch and measure the voltage drop. Should almost be nothing - good.

Hope this helps,
Sherwood

A low-tech explanation: http://www.acmehowto.com/howto/homemaintenance/electrical/multitesteruse.php


A more thorough explanation: http://www.multimeterwarehouse.com/usingamultimeter.htm

Once you learn how to use it, you will wonder how you ever got by without one.

Have fun!

Set the multimeter so that it is checking for ohms, and if you are just checking for continuity you should use the lowest setting, probably 2K or so. Then just place the leads across the contacts of the switch and look at the output. If the switch is open there should be no output which may look like 1. but it will look the same as when the leads are not touching anything. If the switch is closed then it should jump to .000 or some small resistance.

It looks like when the multimeter says 1 your switch is open and when it says .324 it is closed. Im not sure if its supposed to be that way but 324 ohms seems kinda high for a switch

When I bought my Sears multitester, I also picked up a $10 book, Craftsman # 82303. It's title: "A simple and comprehensive Guide to MULTITESTERS and how to us them." A Good book to have, IMO. Seems that the above posts have helped you with your current problem...but this book could easily guide you through other multitester chores. Well worth it's price.