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I have a digital multimeter but lost the instructions for arranging the test wires. There are 2 wires, RED and BLACK. There are 4 ports on the unit; one reads UNFUSED Max 10A, the next reads A, the third COM and the fourth shows V/omega sign.
I have the RED wire in the last port (V/omega) and the BLACK in the COM port. I can check voltage in that set up by going to the V scale.
I recall reading something about checking amperage I had to move one of the wires to another port. Also what setting should I be on if I want to check automotive amperage?
Thanks.

olblu49,

Pretty good memory. To check any current up to 10 amps, move the red lead to the 10A port and connect the meter in series with the circuit you are checking.

Because the unit can only check up to 10 amps, which is a pretty hefty amount, there should be a scale that is marked DCA and goes from zero to 10. This would be the scale to read when patched into the 10 amp plug.

I'm looking at my little cheapo meter and it appears you don't have to select any function with the selector knob...when you plug into the 10 amp port, what you see is what you get, it automatically reads out in the DCA 0-10 amp scale.

Are you confused yet?

Stuart

Stuart

I have been confused all my life but that is another story! On my meter I have 5 scales accessed by a knob/pointer. Volts, an Omega symbol which I assume is Ohms, next is hFE (?) then what I presume is Amps as it starts at 10A and goes up to 200 (with a backward lower case y)followed by what I figure is another Volt scale which has 2 settings, 200 and 750.
If I understand it, with the leads set up as you describe and my needle pointing to 10A on my scale I should be able to read what the amperage is flowing from my battery. That is with one probe into the battery POS and one on the unattached battery cable.
You may have read in another thread that something is slowly draining my battery.
Bill

Bill,

I saw the other thread. I thought the problem had been solved. I'm not sure on your meter, but you have the right idea. Any current (amps) reading must be measured in series starting on the largest scale and working down until you have workable numbers.

Why didn't it work when you tried it through the negative cable...who knows! These are issues that cloud the search so don't try to figure them out too.

I don't know what rig this is on but the original post mentions a SBC which I assume is a small block Chevy. Your Malibu doesn't fit this description, and I didn't think Ol Blu did either.

The cycling on and off sounds like a clock that is rewinding itself. I can't think of anything else that would cycle with such perfect timing. A shorted diode trio (?) in a alternator is a common source for a drain but you say the alternator has been given a clean bill of health. This test to prove a good alternator isn't something that the fellow with the nose ring that works at AutoZone can do...to test the diode trio, I think it must be pulled and checked.

Whatever is causing this is too small to pop a fuse. I think pulling fuses will only be relevant if the leak is between the fuse and switch or device. If the leak is in the wiring BEFORE any fuse or switch, you can't use that method to isolate it.

You are on the right track with the meter...connect it in series until you get a good, mid-scale reading then rattle wires and shake things to see if you can make it disappear.

Stuart

Stuart
You caught on very quickly about the engine. I said SBC to save face but actually its a SBF, a 302 in a Mustang. Actually the Malibu has a real SBC, a 267 incher and the truck is a 235. If you ever hear me say I am going to buy a Mustang - shoot me! These are my buddy's cars, a 66, a 68 and a 70 and as he lets me fly his plane on occasion, I figure I can keep his Pony's in shape.
I think the bottom line here is that the cars are not driven for months at a time and the leak, no matter how small it is, never gives the battery a chance to get caught up.
Bill

olblu; If the cars aren't driven for "months at a time" he needs to buy some cheap trickle chargers to keep the batteries up. Just the normal load from the computer chip, clock, etc. will drain a battery over time. OR, he could just disconnect one of the battery leads for storage.

That is what he is going to do - disconnect. Thanks.

I didn't read your other post that was mentioned. I gathered that you had gone through and pulled the fuses for the accessories and not found the problem. The best way to check to see if the alt is the source of the problem is to charge the battery and disconnect all wire to the alt. If the battery normally goes dead in X days and it doesn't this time, you will have found the problem.
Most of the parts house alt checkers won't catch a problem that will cause a slow drain.
If you look at the 14V from an alternator with an oscilloscope, you will not see a straight line at the 14 volt level. The voltage will have a slight ripple to it, above and below the 14volt line. A volt meter will not show this. If you have a bad diode, every third ripple will drop out. A voltmeter will still show nearly 14 volts and the battery will still be charging. On a car driven every day, you would never know there is a problem. The auto parts tester won't see the problem either.

The backward y stands for micro. It would read MicroAmps or one thousandths of an amp.
The 200 and 750 V scales are probably AC Volts. There should be a sine wave next to the V. Looks like an "S" laying on its side.
The hfe is for checking transistors. There should be a bunch of pin holes marked C,B and E. They will be in no particular order and stand for Collector, Base and Emitter.
Most low end digital volt meters do a poor job of checking current drains like you are trying to do. I know they are suppose to handle 10 Amps, but every one that I've had either blew fuses or melted the circuit board well before the 10Amp rating. If you take the back off you will find a small glass fuse for the current checking functions.

Richard, a wealth of information and questions answered. Thank you. On the 200 and 750 scales these is a sine wave logo and I do have a transistor socket as well. I'll print this out and keep it. Many thanks.
Bill

Cool, except that I screwed up. Micro is ten to the minus six power. One millionth. Milli is one thousandth.

to check amps you will have to install the meter in the line not just acrossed and as it states 10 amps max...doc

most common uses
''the third COM and the fourth shows V/omega sign''

black to com
red to ohms - volts

dial in what scale you need