Test Light vs DMM

[bigaudiofanati2 10+ year member]

So I get a call today from a local car audio shop asking if I want to work a few days. They are pretty busy and need the help. I said sure and was on my way. When I get there I had to do an install on a 1990 mercedes benz e class. It was a simple keyless entry. So I take out my tools and get started. I brought my fluke volt meter as I do with all my installs. The head installer walks over and says here use this it is better and hand me a test light. Now why are these things preferred over meters?//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif//content.invisioncic.com/y282845/emoticons/wow.gif.23d729408e9177caa2a0ed6a2ba6588e.gif

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[bigaudiofanati2 10+ year member]

No one?

 

[Bobby322 10+ year member]

you talking about a continuity tester? Those have helped me alot when my system mysteriously stops working. Ez to tell what wire is bad

 

[Vegas WRX 10+ year member]

A test light and a fluke are no where near the same thing. Why would he tell you to use it? Unless you were just using the fluke to find positive and negative, or constant power or power at ignition or whatever. Then a test light would be fine.

A fluke is used for so much more that a test light could never dream of doing.

 

[x1le 10+ year member]

don't test lights backfeed with the potentional to fry electronics and set off airbags if you probe the wrong wire?

 

[Yeah Toast 10+ year member]

Well I'm a diesel tech and I work on coaches with a multiplex wiring system. If you use a test light and maybe touch the wrong thing it will kill the box (box cost 1800-2400), unlike a multimeter were I could touch all the wrong things I want and be just fine. But if you were looking for easy stuff, on not so sensitive equipment, such as nick06tC said then a test light would be pretty ideal/faster.

 

[Vegas WRX 10+ year member]

They shouldn't, all they are, are a small bulb (or led)with a positive probe, and a negative wire (alligator clip). if there is power through a wire it completes the circuit to the bulb and it lights up. No power and it doesn't.

 

[Vegas WRX 10+ year member]

Yeah toast, is it caused by the load the light puts on the system freaking things out?

 

[x1le 10+ year member]

I just remember a couple questions about why not to use test lights on my mecp basic //content.invisioncic.com/y282845/emoticons/crazy.gif.c13912c32de98515d3142759a824dae7.gif

 

[Vegas WRX 10+ year member]

Do you remember the reasons? I am curious. Basic electrical, as far as I understand, says there shouldn't be an issue. Unless the bulb acts as a resistor and changes how much resistance there is causing something to fail by running to high of amps to whatever it feeds.

Kind of like if a car amp is 1 ohm stable and you add a circuit inline that drops it to say .5 ohms, it could burn it out. But a test bulb is not pulling much resistance to do something like that.

 

[dman4486 5,000+ posts]

http://www.bcae1.com/testlite.htm

 

[PaulD 10+ year member]

The head installer walks over and says here use this it is better and hand me a test light. Now why are these things preferred over meters?//content.invisioncic.com/y282845/emoticons/confused.gif.e820e0216602db4765798ac39d28caa9.gif//content.invisioncic.com/y282845/emoticons/wow.gif.23d729408e9177caa2a0ed6a2ba6588e.gif

probably an "old school" installer that has just been lucky so far

 

[Vegas WRX 10+ year member]

http://www.bcae1.com/testlite.htm

Good article and a worthwhile read for everyone getting started in car audio!!

I wish it explained why tho. I am all about learning the whys to stuff like this.

Thanks for the link!!

 

[finkster 10+ year member]

a DMM is almost always better than a test light. Most DMMs will pull nowhere even close to as much current or amperage as a test light, safer for computers //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

I have no clue what the peeps at your work are talking about.