Howdy!

I misplaced my manual to my multimeter, and need to find a cause for draining our bus batteries! (small enough that over night it starts, but over a three day weekend batteries are at 8.51v!)

I assume that I want to use the section I have circled in red, but what does the "m" mean?

Where should I start? 2m . . . 200m?

Why would only the 20m have a little red 10a next to it? And would I use the red probe in the other side socket which is also marked "10A" in red?



I know that there are some smart people here that can get me going in the right direction!

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82 240D Manual 277K and still rolling!
02 Volvo S60 AWD For Sale

Use the 10A (ten Ampere) setting to begin. Don't use any setting with "m" because that is milliamp (thousands of an Amp).

Move the red cable to the special place for 10A, and set the dial to measure DC Amps. Leave the black cable in its only spot.

When the meter is setup like this, NEVER use it like a volt meter. Never touch the red probe to battery + and black probe to battery (-). You will instantly snap the fuse the meter, or blow the meter.

What you have to do is put the meter in-line with the circuit you want to test. For example, pull the ground cable off the car battery. Clip your meter red probe to the negative battery cable and clip your meter black probe to the negative battery post.

You can only safely test things that draw up to 10A with this meter. If something draws more, you snap the meter fuse. So don't try to start the car while configured like this.

Just sitting there, you should be able to see what the steady state draw is on the battery.

Tip: turn the meter on first, then connect in-line as described. You will probably see a higher spike for a few moments, then the number will settle down to something smaller. On my car, I think after about 30 seconds it falls to steady state. What is happening when you first connect is all circuits in the car boot up, which can include turning on interior lights (that later fade off), the radio, an alarm, etc.. You might see a couple amps draw for the first while, then settle down to something less than 0.25 amp.

0.25 amp by the way, is enough to flatten a battery in a week.

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Cheers!
Scott McPhee

1987 300D

This is on a 05 school bus with two type 31 batteries hooked together . . .

Is the 10A / 20m setting the same do you think, or is that whole amp section (2m, 20m, 200) all protected to that 10Amp rating?

Here is a picture I thought I had also posted . . . kinda hard to see but the left jack is labeled "10A" in red.


Any idea what those "NPN", "PNP" and the funny little arrow are for?

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82 240D Manual 277K and still rolling!
02 Volvo S60 AWD For Sale

NPN and PNP are types of transistors (basically, the type of doped semiconductors)

http://en.wikipedia.org/wiki/Bipolar_junction_transistor

That symbol should be for a diode.

http://en.wikipedia.org/wiki/Diode

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1982 240D, sold 9/17/2008
1987 300D TurboW124.133 - 603.960, 722.317 - Smoke Silver Metallic / Medium Red (702/177), acquired 8/15/2009
262,715 and counting

The 10A / 20ma setting is the same on the dial. The difference lies in where you plug in your red lead. If you plug it into the 10 jack on the meter, then you are set for the 10a range (different fuse). If you plug into the ma jack, then the current you are measuring had better not exceed 20ma or you will blow a smaller amp fuse.

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John Schroader
bio burnin' 83 300D, '83 300 SD, '79 240D
"I've never met a man who was good at making excuses who was good at anything else" Ben Franklin
"You cannot permanently help a man by doing for him what he could and should do for himself" Abraham Lincoln

OK, so . . . I blew my 10 amp fuse (or it was already blown!)

I had it set to 10A and the red probe plugged into the left socket, I disconnected the + wire off the battery and put one lead on that and the other on battery cable, no reading . . . eventually I pulled to fuse and tested it and it was bad . . . so . . . I took a 8A fuse for my mb (didn't have a 10A) and put that in . . . found a 7.5a fuse in the bus which went to the radio, turned on the radio, and pulled the fuse, radio stopped, I then put a probe from the meter into each end of the fuse holder, and nothing . . . think my meter is dead?

The bus goes through some kind of self test when ever you go to start it, and after you shut it down sounds like it is the ABS? it's a whirring motor sound and some clicks . . . it does this same thing when I reconnect the battery cables . . . little sparks too . . .

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82 240D Manual 277K and still rolling!
02 Volvo S60 AWD For Sale

Shawn, I found the HHM90 manual for you, they didn`t have the HHM93 but close.


http://www.omega.com/manuals/manualpdf/M2781.pdf


Charlie

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there were three HP ratings on the OM616...

1) Not much power
2) Even less power
3) Not nearly enough power!! 240D w/auto

Anyone that thinks a 240D is slow drives too fast.

80 240D Naturally Exasperated, 4-Spd 388k DD 150mph spedo 3:58 Diff

We are advised to NOT judge ALL Muslims by the actions of a few lunatics, but we are encouraged to judge ALL gun owners by the actions of a few lunatics. Funny how that works

Thanx Charlie!

I did go to thier site, but couldn't find it!

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82 240D Manual 277K and still rolling!
02 Volvo S60 AWD For Sale

If you put your meter (set up the way I said) in-line where the radio fuse was, and got dead radio your meter has a blown fuse or is not functioning right. Your radio has a 7.5 fuse and your meter is a 10A setting, so your meter should handle all the power your radio can suck.

It's super easy to pop 10A fuses in meter over and over again while you're doing this kind of diagnosis. If the bus does some kind of motor whir when you first connect its batteries then chances are it is pulling more than 10A for a brief moment, and pop goes another meter fuse.

You're going to have to start working at a finer scale than "whole bus at the battery". Pulling lots of major fuses from the bus fuse box is an easy way to eliminate circuits in big strides. Alternately, pull a fuse and use your meter across the fuse holder contacts to see if that circuit is culprit. You should be safe on any fuse that is 10A or less (duh), and you might want to get a meter capable of more power like 30 - 40A for doing automotive diagnosis like this.

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Cheers!
Scott McPhee

1987 300D

One trick I learned a while back for chasing power drains:

To avoid having the surge blow the fuse when you connect, try connecting the meter to the battery cable while the terminal is loose, but still on the battery post. Then lift the cable free of the battery, while keeping the meter probes connected to the post and the cable end.
You should then be displaying whatever the leakage current is, without having any of the power-up current surge that you get when you first connect the cable to the battery, and likely will be able to read it with a 10A range meter.

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-Josh
Testing the cheap Mercedes axiom, one bolt at a time...