might give you trouble, disconnect the negative leg to the battery and put your volt meter on the 10 amp scale between the cable and the post.
Everything has to come back to the battery through the negative cable. Check the meter and record your readings as you turn different items off. If you get everything turned off and still have a reading then either you missed something or you have a problem between the battery and the master switch. Once you check every thing on the 10 amp scale do it again on the milliamp scale. Doing it on the 10 amp scale keeps you from frying your meter if it's a cheepo meter and you missed something with over a couple amp load. Most likely you didn't but it's a good hsbit. Good luck.