Today I went to work and the CD player worked fine. Went to lunch and it worked fine. Got in the car to come home and nothing. I've checked all fuses, grounds and power wires. I do think I have tracked it down to being the diode in the accessory power wire though. I've got power on one side of the diode and nothing on the other side. Is it possible for a diode to go bad? Is mine bad? Or is this how a diode is supposed to work? I have no clue what a diode does. lol. The only think that still stumps me is that I took the constant power wire and ground wire from the Head Unit harness and hooked them up to my battery charger and still had nothing. What do you guys think THANKS A TON. By the way it's the Pioneer DEH-8400 Head Unit. Thanks again.

Rich.

 

just check the red 12v ignition, the yellow 12v constant, then check the 12v with your decks ground to eliminate a bad ground if all wires show 12v's and the ground is good, check the fuse @ the deck. If the fuse is good then check all fuses under the dash and under the hood, if all the fuses check out then more than likely the deck just went out.

 

U Know Rich, I Own a DEH-840MP which it practically the same HU. Honestly I want to beat the Sh*t out of it like the copy machine in Office Space. The thing will randomly shut off and spit the CD i was listening to out, then sometimes it doesnt wanna let it out, and even somethimes - get this, the buttons go into what i call SUPER SENSITIVE MODE. That is when I barely touch a button and the HU will sum how think i am holding my finger on it. For example i barely touch the right seek button and it will skip, and keep on skipping unless if i press the reset button. I will kill the deck - oh i will someday and hoefully i will have the money to build an in car computer with a touch screen

 

Yeah, I've had alot of problems with mine too. Face won't fold down, it won't turn on. Won't eject CD's. I will never own another Pioneer.

 

http://www.carstereo.com/forum/showt...tid=2498&fid=5
Go to this link, look for the post from Magazz. My 840mp was doing some of the same stuff, this $11 kit fixes it, and you can do it yourself. No soldering, just need some rather small phillips head screwdrivers. This is a very common problem on the 8400-840's. The part number is GXY1005 on Pioneer's website.
Good luck.
-John