Hi there,
without DVM, no can do.
You need to disconnect the negative bat. cable and put the DVM between cable and bat. terminal. It should show the drain. Then disconnect the various circuits one at a time by taking out the fuses until you find the circuit that drains, i.e. you found it when the drain stops.
There is probably a longer and more detailed write-up in the archives.
You also need the DVM to see whether the charging is ok. With engine running, voltage on my Mazda is above 14 V, yet over time my bat. looses the charge.
I figure I don't drive it enough and now just connect a charger for a few hours whenever I feel the starter not turning strongly anymore.
Hope this helps
Reinhard

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Reinhard Kreutzer
1987 420 SEL (126)