My Cd player will lose all power randomly, the red security light wont blink or anything so its getting no juice from the battery then either the very next morning or the day after my 4Runner will not start due to low battery. So something funky is going on with the electrical and im assuming that the aftermarket CD player that the previous owner installed has something to do with it.

Im not sure exactly how he wired the Cd player, electric fan and fog lights but it looks like he has a couple relays (black box lookin things) and fuse box looking device mounted at the back of the engine bay, he also has the neccessary wiring running off the battery towards the back of the truck for an amp and sub setup, so the wires are just strung through the truck with no destination yet.

What could cause the CD player to lose all power but nothing else and then kill my battery over night? also, it only seems to do this in the summer, I dunno if thats coincidence or not.

Oh and to clarify, once the battery dies and then gets boosted, the stereo works fine until it happens again randomly. sometimes it takes a couple days to happen and sometimes it takes months to happen again.

first off, what brand stereo?? depending on what brand, may be the reason. a good quality brand, Kenwood, pioneer, alpine, would work better than a cheap off brand like Dual, or something like that. also check your wiring. it may be that something is coming loose and grounding.

Since it happens so infrequently it'll be hard to diagonse.
The CD loosing power seems to be an early indicator that the battery will go dead if I read it correctly.
Next time that happens, connect an ammeter inline with the battery pos (+) cable to monitor current drain. Normal drain would be 50 mA (.050 A) or so.
If it's say 1 A or more start by disconnecting the add-ons like the CD, lights, fan, etc.
If no change start pulling fuses to isolate the circuit causing the problem.

Thanks, I'll give that a try and see if I can locate the reason for the drain.
electrical gremlins are the worst, especially when prevoius owners just wing it and dont do things correctly.

The most common cause of of electrical problems is aftermarket trailer wiring.
I see it all the time.