What do you guys use to test available voltage/amps at a specific part? (like i want to see if my window motor is getting enough juice)

I have both a volt meter and a test light available.

You can tell alot with only a voltmeter. Amp draw can be inferred by your voltage reading, component reaction. Ohms law has 3 variables. On our trucks, 2 of them are constant, volts and ohms. When we have electrical problems its always one or the other. Lack of voltage means high resistance, either from the component using it, or wiring problems.

Put your voltmeter on the wires at the window motor and see how much of a drop you get when running the motor.

-Will

yeah, i have a test light that i get by with for most things. im gonna go pick one up from sears this week. do you suggest a particular model?

what do you think about this?

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03473754000&subcat=Multi-Meters%2C+Testers+%26+Accessories

Overkill IMO. MY 5-10 dollar hamfest special has worked great. Unless you have plans to use all that fancy shmancy stuff I'd save the money. The only thing I wish I had was a frequency thing to meausre the MAP output. But thats the only sensor I cannot test with my 5 dollar multimeter.

Accuracy is so good with meters nowadays, plus with our trucks, a tenth or 2 of a volt (which is a HUGE margin of error for a meter and you probably would never see it) wouldnt matter anyway, what with the resistance of aging wires and all.

-Will


Just make sure its in a protective rubber case. You will drop it workin on your truck, as me how I know :-)

I really want a voltmeter. So far everything I've done I've used a test light for. I'm carb'd still so I think I can get away with it.

this a little less overkill?

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03481437000&tab=spe#tab

The one i use at work was a craftsman model i paid 119.00 for, i also use it for three phase 480.

You should be able to run to home depot and find one for 19.99. Your just testing DC voltage just make sure that it has that option.

this a little less overkill?

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03481437000&tab=spe#tab

Yea as far as options go thats more than you'll ever need, which is how most multimeters are nowadays anyway.

50 bucks is still a little pricey, you can find another one just as good for 20 bucks like Bronco Rob said.

once you use it, you will find yourself delving into other things like checking 110V at places you're having house wiring problems, vacuum cleaners, toasters blah blah. My dads a PHD in electrical engineering and he, to my knowledge, never used all the functions the cheap multimeters have when working on cars or around the house. Its just not necessary.

-Will

What do you guys use to test available voltage/amps at a specific part? (like i want to see if my window motor is getting enough juice)

Use a volt meter. You need to see what it is when the motor is functioning and you need to look at both sides of the motor. One wire should have near battery level voltage while the other wire should have no voltage. If you have a voltage reading on the grounded side you have a poor ground. If the plus side is low you have a high resistance path in the feed, (considering that your battery is good). The thing you need to keep in mind is that the wires swap function to change the direction of the motor.

:thumbup

ok guys, i picked this bad boy up at sears a few minutes ago

http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03482139000

i tested a few things.....
with the truck off, i have 12.5 volts at both my batts
with the truck on, i have 14.6 volts at one batt and 12.5 at the other (its isolated)
when i tested amps at the batts, i got a reading of 5.something....obviously it has more than 5 amps if i started my truck up....must have tested wrong.
at the solenoid im having a problem with, i have 10 volts with the truck off and 12 with the truck on. it was drawing 4 amps with engine off and 5 when on. the solenoid wasnt popping either time. it has a 40amp fuse rating.

i have no idea what any of that means. could someone explain? i can test other things if that would help.

You cant test starting amps with that thing. Its got a 10 amp limit. Besides, current draw is almost pointless to measure directly since you will be introducing resistance to the circuit, and affecting your reading.

No multimeter I've seen will test 100's of amps. If you really want to know current draw, get an inductive meter that clamps over the wire.

-Will

i figured that. any idea about the voltage thing?

i figured that. any idea about the voltage thing?

with the truck off, i have 12.5 volts at both my batts
with the truck on, i have 14.6 volts at one batt and 12.5 at the other (its isolated)


12.5 is normal for a well charged battery with the engine off. 14.6 is the voltage level put out by the alternator. The voltage level at any point will be determined by the voltage drop caused by resistance to that point.

for example: Say you have your engine running. You measure the 14.6 volts at the head lights with them off and 10.0 volts with them on. That indicates that there is a high resistance in the circuit is causing a 4.6 volt drop. (That is not unheard of in a standard Ford headlight circuit by the way. Ford hangs a lot of other stuff off that circuit ahead of the head lights and the circuit length is pretty long). Now if that happened after you did the headlight wiring upgrade, you have a problem in the wiring, perhaps you didn't use a heavy enough gauge wire for the currrent draw of the lights, there is a bad connection, relay contact is bad, etc.

Another thing is voltage is a good positive way to trace out a circuit if something is not working, see previous post in this thread.

Hope that gives you an idea what the voltage readings can mean to you.

Good luck and good metering,

:thumbup

I suggest this one
http://www.sears.com/sr/javasr/product.do?BV_UseBVCookie=Yes&vertical=TOOL&pid=03481337000&subcat=Multi-Meters%2C+Testers+%26+Accessories

you cant go wrong with flukes. They are reliable, last a long time, resistant to getting droped, and are easy to find fuses for. I use mine alot for work so I spent a little more money to get a better one.

Thats another thing when you go to measure ohms make sure there is no power on that circuit. If there is you will fry the fuse in the meter.

thanks everyone

I don't think I'd bother with a Craftsman multimeter unless it was an inductive -- and the one Craftsman inductive I bought I just had to take back after three weeks because of an internal dead short. So much for that.

I have a very nice high impedence meter I can use for testing sensors, but I can do 99% of my automotive and household work with a cheapie Centech digital meter I picked up for $3 at Harbor Freight. Well, let me clarify, that I picked up four of for $12 at Harbor Freight. For that cost, I have one "disposable" meter each to keep in the Bronco, the Mustang, the bike, and the garage -- yet for $3 apiece I haven't had a bit of trouble with any of them, and my nice meter mostly collects dust. :thumbup

Most any meter sold today is drastic overkill for 99% of automotive applications, the only real exceptions being checking a couple of coils and sensors that require a high impedence.

Oh, and I've been making fun of a friend for six months for having gotten suckered out of $20 for a test light, just because it says "Craftsman" on the handle. I wouldn't pay more than $5 tops for anything that's basically a light bulb with an alligator clip and a probe, and $2 to $3 would be better. :toothless