I can't figure it out.. I feel like there is an electrical nightmare going on in the truck and many searches have turned up nothing exactly like what I'm experiencing. First off, the voltage meter is always dropping whenever you use the power windows, brakes, ac (especially! from like 14 to 10), and all the interior lights dim and if you use the windows, and the dash will display the ABS light and cause some other lights to come on when the voltage drops too low. The AC works fine when its on and while you are driving, but at idle, it slows down and will sometimes blow warm air.. The service 4wd message comes on only when I use the AC and it engages fine when its not on, I haven't tried to engage it when the message is on, but I assume it would work anyway. I've checked the battery connections and alternator ground but I'm not convinced that's it. I also believe that its not the alternator, because they usually work or they don't, and mine's working for the most part. There is an aftermarket radio installed (with a wire that goes into the drivers side fuse box jumped off of a fuse? which I think is weird) and the whole dash cluster was replaced with a new one right before I got the truck. Any thoughts on what might be happening here? I'm pretty mechanically inclined and do most work myself, but I'm not an expert, especially when it comes to electrical stuff. Thanks for any insight!