DMM ... A BASIC TOOL YOU NEED

[bertsmobile1]

I find the only problem with a test light is most will light at 8 volts , some even less, at least a DMM will read the true voltage of the battery ...... knowing I have a GOOD battery saves a lot of headaches. If I have suspected wiring or switch promblems I " jumper " right from the battery to the starter , of course thats AFTER checking oil, fuel and spark plug for spark . My DMM has a continuity beeper ( very handy ) and has been really helpful in many cases especially when checking a wire end to end ( can't do that with a test light unless you have voltage present ) . But I'm not here to "try" anybodys knowledge or skills ......... I simply want to help others ..... AND ESPECIALLY ..... the MEMBERS OF THIS SITE , who are trying to help all those that are seeking answers.
The tutorial in my original post covers the basic operation of a DMM , BUT then it does start getting into the "SCARY " part for most novices Actually .... voltage & continuity are about all I use that meter for , come to think of it !! Anyway ...... GENTLE - men ..... ya'll have a FANTASTIC day ...... Boobala .......:2cents:

By the way folks , check the prices on those DMM's in my original post , so ya do without a few beers , better to have the tool and not need it , than sit there wishing you DID have it , it's NOT a bank breaker and most people can get one easily .

yeah,
Some times you do need to know the vactual voltages but for at least 75% of the enquires we get here a yes/no is more appropriate as the owner is oft not mechanically literate which is why they are here in the first place.

 

[Mad Mackie]

And then the phrase "high impedance" is brought up with DMMs!!!!:confused2:
One guy asked me what a high impudent multi-meter was!!! :mur:
I wanted to say that it was a meter that misbehaved too often, but I didn't want to insult him!!:laughing:

 

[motoman]

Mackie. Like I said the high Latin such as "impedance" etc is very frightening to novices. So they should stay with DC (direct current ) to start, That means ignore the setting on the DVM which say AC and has the little squiggle sign . Electricians use some different instruments than tractor mecanics, like the clamp on (lobster claw) current meters. Novices , don't look at the forest , just the tree in front of you to start.:smile:

 

[cashman]

Used to you could get by with just a test light. Now with EFI and electronic control modules used in safety systems etc. you do need a good digital meter. Even a good laptop in some cases. I taught small engine mechanics part time for 20 years and some students would show up in class with new $300 Flukes without any knowledge about what the meters would do. And some of the instruction books that came with the meters seemed to be written by rocket scientist. When it came to electrical, we always tried to teach the "why" part first and it seemed to make the "how" part a little easier to understand for the students. It takes a little practice in diagnosing electrical problems. Your not going to learn to play a violin by reading a few paragraphs. Some of the posts on here simply want to know "what color wire goes where". That might be easy for someone who is familiar with that particular equipment. But for the rest of us, it takes a little thinking and a little practice.

 

[motoman]

cashman, Well said. For instance many probably wonder why the current measurement is different from voltage. Answer after a little reading, "current" moves, voltage is a kind of pressure point measurement. Also good point on those with EFI (electronic fuel injection) where the trouble shooting guides will put out some voltage values to look for at certain connectors, and like Berts has told us , getting a current reading on a PTO to see if it is ok . By the way a Fluke is great , but for home use you can get by with a $25-$35 DMV and it may even have temperature probes thrown in (Harbor Freight has a couple units which get good reviews, even by pros) I do not endorse all the HF stuff and do not own stock.:laughing:

 

[Tinkerer200]

You can get a simple VOM free at Harbor Freight occasionally with a coupon and often with any purchase. A VOM across the posts of a battery with engine running will tell you if alternator is working properly while a test light won't. I virtually never use a test light anymore.

Walt Conner

 

[motoman]

Re getting readings that vary a little from a value in a factory manual..such slightly different results will be understood after a little experience. Nothing is absolute just as in everyday life. Also a little motivator for those without the DVM. Although I suggested not to worry about the AC part of the DVM switch settings you can use that setting to check household electrical outlets by placing a the ground probe tip (black) on the metal base and the other into the bayonette connector contacts. So the DVMs have more than one use. On the continuity setting (ohms-beep sound) you can check out a suspect switch by wiggling the contact lever or simply observing an "open" where you expect "continuity." An internally corroded battery cable: Should have almost no "resistance"... check it with the ohm setting. On and on. As stated you do not have to spend over $35 for a decent DVM. I have used the freebies H Frt has and they might be enough to get a newbie started (even though they lack decent current measurement range.)