When you said that you wired ACC and On to the same switch, does that mean that you tied the BR and YE wires together? If so, I'm not so sure that's a good idea. If you don't want to use an extra switch and want to activate them both (actually I'm not so sure you even need the ACC), you can use a double pole switch, it's basically two switches in one housing. Kind of like this:
View attachment 22359
But in the mean time, try disconnecting the Brown wire to the ACC to eliminate that circuit and see if that helps.