Finding a voltage leak

[mihit]

^^ This

With the ignition off just disconnect the battery negative and clip a multimeter in series with it on 10amps.

Just for clarity: that could be labelled DCA or DCI, and on most meters you will need to swap the red lead from the "voltage/resistance" plug to the "10A" one.
If your meter isn't auto-ranging, start on the highest current option (10A), if nothing shows up, or you get a reading like "0.1", or a reading that flicks between 0.1 and 0.2, go to the next option which may be 5000mA or 1000mA which will give you greater resolution. ie 0.1234
About a quarter to half amp should be acceptable with a good battery (<250-480mA)

- and don't forget to swap the red lead back immediately you've finished! if you try and measure voltage with them in that configuration you're going to pop the multimeter fuse.

If you find that the parasitic draw is high, before diving too deep and pulling wiring apart, you can pull fuses and relays to see if it drops.

I got one of these which is handy for just that:
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