hey guys.

i was on an audio forum, and last night, one of the guys couldnt find a 12v turn on and a 12v switched. he was confused about learning how to use a multimeter so i told him to buy a light test. i think they still sell them at napa and other car places. but i used them when i installed my audio equipment on my w209 and it worked out just fine.

then i got this big audio head who is actually a certified installer going off on me that i shouldnt be using a light test because it might fry the computer or deploy airbags...-_- i never knew this could happen. and he went on about it should never be used on any cars today and especially an audi.

so my question is, is a light test too old of technology for DIYers. haha i didnt know we all had to buy multimeters now.

 

I would definately NOT use one on anything made after, i dont know, say 1990???.....if you probe the wrong wire...say you hit an air bag wire in the steering column bundle of wires, it will ground out the bag, and set it off, and that would be a very costly mistake...to the tune of several thousand's of dollars to replace everything..learn to use a multi meter, its your friend.

 

lol. interesting. i think i'll get my hands on a multimeter but i was trying to find out which of the 3 wires on the cig lighters was a 12v turn on. and on top of that, one of the mercedes tech that had a previous job working on car audio told me to use a light test. so i listened.

i didnt go probing around and every wire, i kinda knew the general vicinity of wires (the 3 at the cig lighter)

 

lol...obviously, your probably not going to set off an air bag by testing the cigarette lighter, they DO work, and work well, but with todays cars being computer controlled, and not just a battery , alt, power wires and some ground wires, just be careful when probing unknown wires.

 

A test light is still useful on todays vehicles. Multimeter or Oscope would be the first choice.

a test light with a high impedance would work fine on any vehicle, however, the test light with a light bulb in it draws a lot of current and could damage a circuit. I do audio also, and for a very long time, worked on electronics from missile launcher to nuc tomahawk cruise missiles... tell him I said not to get his panties in a wad... as you successfully found what you needed utilizing a test light without damaging the vehicle... you can also add....... because the pro installers near you t-tapped every connection and used crimp caps because they all suck....

 

lol yeah i got another one telling me that all their pro installer friends dont use the test lights but essentially, thats what i told him.

i told him i found what i needed for using a forum, wiring diagram, and a test light and guess what, no comp error, no airbag deploy. i by means no pro. but i got the **** done for .95 cent tool and i didnt run into problems cuz i did research beforehand rather than trying to probe every wire to find a switched and constant 12v

 

If your "light test" tool draws reasonable current, it actually should be safe for almost anything.

I'm sure you would not use it for airbag wiring anyway and even there it actually would not harm if used properly.

It is perfectly OK for any power source. It would fool several signal lines if the impedance is too low but all of those should be built to tolerate short circuit (without blowing off) and your light test cannot have lower impedance than a short circuit. Of course a too high load on a signal could confuse a computer but not permanently.

Personally I never use a light test tool, just multimeters and oscilloscopes but it does not mean the tool could not be useful sometimes.