I wouldn't do it that way myself..
are you looking for a significant key-off current drain ?

if so, I like a plain ole 12V test light.
It's very possible a small digital volt gauge wired in full time to Batt +
may not show with your current meter.
Vanagons usually have a clock wired in to Batt + as well.

the electronic guru's may comment more in depth.

what symptom are you seeking to repair or address ?
your basic method sounds all right ..
amps don't have negative or positive ..so I wouldn't think polarity matters
in a digital read out on DC current.
Good ole test light is very useful in this type of test.
Did you RTFM ?  .............'read the manual' for the meter ?

Scott

----- Original Message -----
From: "Courtney Hook" <courtneyhook@SHAW.CA>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, October 21, 2011 5:03 PM
Subject: Multimeter help for the idiot

I was trying again to see if I had any current draw so did some internet
sleuthing to help me figure this out. I can rebuild engines fine, tune
motorcycles, etc, etc, but when it comes to multimeters I am an idiot. I
think I did it right, but want some backup on this. I put my MM between the
+ terminal on my new battery and the + cable. I then set my RadioShack MM to
the notch marked 200 DCmA which also had a solid line beside it with 3 dots
under it. I then took the reading, and it said 00.0 ??? I reversed the leads
and it then said -00.0
Does that mean I have no current draw at all?? I am lost, because I have a
small digital volt gauge plugged into the lighter that MUST be drawing
something??
 The MM reads voltage across the battery fine, at 12.74volts, so I think
it's working fine. What am I doing wrong??
Courtney