Can Somebody Explain How To Use A Multimeter

[yanto 0]

As title-bought multimeter to check things when the go wrong but it didnt have instructions on using it. Any electricions on here for a quick guide or any info?

 

Cheers J

[jimistdt 1]

Any good?

[Cameron 16]

Here's the very basics..

 

Voltage test - select the correct range and AC or DC voltage, so 20VDC for most automotive stuff. You test voltage accross the circuit, so from +ve to -ve.

Eg: battery voltage will be 11-12V, about 9V when cranking, and about 14V when the engine is running.

 

Current test - test it with the circuit open, so between +ve and +ve. Don't test accross the circuit (+ve -ve). This is a good way to test for parasitic drain (if your battery keeps going flat) disconnect the positive and test for current between the positive terminal and the positive lead, it will show you how much current is being drained with everything switched off.

 

Resistance - test across the component.

Eg: coolant temp sender is usually thousands of ohms and decreases as temperature increases, so a good way to check is to note the resistance when the engine is cold and then compare it to when the engine is hot - there should be a large difference.

Components with coils (injectors & crank sensors) will generally be quite low resistance, high readings will suggest something is up.

 

That's basically all you need to know for a wide variety of tests!

[ablister 31]

do not test resisitance on air bag systems (incase you ever wanted to!), the meter sends a small voltage down the citcuit when it does it's resistance check, and could trigger the air bag

[platty 1]

Only thing I'd add to Cameron's very informative reply is to start high on the scale for resistance testing, and click it down a setting to move the decimal point, if your reading lots of zero's before you get a numerical value. Otherwise you'll get 'over level' readings that may confuse you.

[Alfie 6]

As title-bought multimeter to check things when the go wrong but it didnt have instructions on using it. Any electricions on here for a quick guide or any info?

 

Cheers J

If you google it, "How to use a multimeter" quite a lot of info and bedtime reading there