Seattle Scott

If it's an analog meter it will "peg" left or right and probably blow a fuse, if it's digital it will read something like "+1.999" or "-1.999" or "OVER RANGE" and probably blow a fuse.

In this particular case I think it's because the high current range on meter usally has a seperate input so there is no input to the lower ranges.

Spanglear

His third meter is OK so far as I can tell from the post. He said that he put it on the 20A max. scale and read 3.8A THEN tried the lower settings (400mA & 4mA scales) and it wouldnt register the 3.8A (As you and I might expect).

Ben, This is because the the max. you can read on the 400mA scale is 400mA which = 0.4A, and the max. you can read on the 4mA scale is 4mA which = 0.004A, far less than the 3.8A current there. Whether you have blown the third meter or not I dont know, but you should really always start at the high scale first.

My multimeter works the same but just displays "1" in the far left when it is out of range. My problem is that I keep forgetting to turn it off when I have finnished!

HTH

Ben90S

beacause it still functions on the 20 amp setting, i was just trying the lmilliamp settings to see it it would read anything, but yes very soon i will be pullin gout all the fuses to find the culprit, ive already tried the ones i was suspicious of, and they check out ok. The only problem is if i cant find the problem i may be forced into selling the car, which i definatly dont want to do. Ill let you know how it turns out.

Spanglear

If it still works on the 20A it is OK. Its probably internally fused to a maximum of 20A.

Because the current you measured was higher than 0.4A (400mA) and .004A (4mA) it wouldnt register on the readout. It is just too high for those ranges to display it.

Hope you understand & sort it soon!

Seattle Scott

Look at this meter. The lower left terminal is the 10 amp input. It isn't fused, only the low current stuff is fused.

Ben, does the meter have a seperate high current input?


<img src="http://www.fluke.com/images/87_150_p.jpg">

Spanglear

Sorry Seattle Scott, Just checked my largest multimeter and the 10A part IS indeed separate and UNFUSED. I guess I was getting it confused with the smaller one I also own.

The smaller of my two multimeters is nothing special, and has only one input for measuring AC & DC voltage, Current, Resistance. It will measure currents up to 2A and has 4 scales: 2A, 200mA, 2mA, 20uA. I have measured currents using the wrong setting before but it just displays "1" in the far left corner to indicate that it is out of range. I'm pretty sure it is fused to the maximum it can handle i.e. 2A.

To my mind, all you are doing when you change from one range to another is looking at a different part of the logarithmic current scale, and if your reading is higher than the maximum of that range, it cant be displayed. If it were lower, you would either get no reading or an inaccurate rounded-up value due to the poor resolution.

Anyway, rather than debating the correct usage of electrical test equipment ad infinitum, maybe we should just agree to disagree and help the poor guy who is in the poop at the moment ;-) Still there Ben?

Ben90S

it has a sperate 20A terminal where i i have the red wire connecting.

Ben90S

Re: and also, it says "fused" under it

Seattle Scott

hooked up to anything. ( The positive lead is only hooked up to the 20 amp input).

Seattle Scott

really bad. The resistance of the 20 amp current shunt in relation to the fuse is low enough that you can't get an accurate measurement.


I think the "Fused input" or whatever is referring to the smaller current range input, that's probably the ohms and voltage input too.