i bought my 05 evo 8 in april. and decided to switch the head unit out it already had a aftermarket head unit in it. so i took it out with the wiring harness adapter and unhooked al the wires and hooked my new unit into the harness. then installed it. head unit works fine. but it dont turn on with the key or shut off with the key have to turn it on and off on the unit itself what wire did i **** up? the other unit turned on and off with the key. also i just went out to look for somethign and noticed my battery is DEAD im beleiving th head unit is the cause i just put the head unit in the day before yesterday the car sat for one day please help!!! p.s sorry it their is already a thread on this i did not see one. im still a newbie to the evolutionm

 

any ideas atleast?

 

Easiest thing to do is grab a multimeter. If you using an aftermarket wiring harness there are only three colors you need to look at for power.
Yellow- constant 12v, should have power all the time.
Red- switched 12v, should show no power when the key is off and 12v in acc and ignition
Black- Ground.
Take a look at your wiring and post back results.

 

figured out the problem. i did hook them up right the first time but apparently when i took the old head unit out i grounded somethign out and blew the fuse under the hood. i had to have the yellow wire from car harness with the red and yellow on the head unit for it to work which would b constant power. replaced the fuse hooked the wires up right now it works how it should thanks Marcas.