[moxxoff]

Originally Posted by ctuna

"But the factory headunit would not power on, the fuse in the back is good, the lights around the headunit would light up, thought was an issue with the headunit being dead so swap out to an aftermarket Alpine headunit from my E30 that was working fine, but notice it would not get power to turn on, there's no power in the 12v battery and 12v ignition wire.

Then swap to new battery, coded accordingly, but still no power.

Truly at a loss on this one."

Measure the 12 volt line from the back of the Radio connector to the Fuse with and ohmeter.
Do the same for ground line on the to ground from the back of the radio connector to chassis ground.

Possible the relay that control's power to the radio in the fuse board may not be switching.
Read the first electrical pdf

You should be able to measure power and ground at the back of the connector .
Since you used a aftermarket radio did you have a harness to make it work or did you hack
up the factory harness in the car?
Did someone else hack up the factory harness?
Why would you think the harness pinout would be the same between an older car and a newer car?

There are two fuses the one on the back of the radio and the one at the fuse board behind the glove
compartment.

head unit
http://www.e90post.com/forums/showth...ight=head+unit
http://www.e90post.com/forums/showthread.php?t=1457320
http://www.e90post.com/forums/showthread.php?t=1036190
http://www.e90post.com/forums/showth...hlight=dynavin
http://www.janus-design.net/english/
http://www.e90post.com/forums/showthread.php?t=355089
http://www.e90post.com/forums/showth...ight=head+unit
http://www.e90post.com/forums/showth...hlight=dynavin
http://www.e90post.com/forums/showth...hlight=dynavin
http://www.e90post.com/forums/showth...light=retrofit
http://www.e90post.com/forums/showthread.php?t=993447
http://www.e90post.com/forums/showthread.php?t=1016187
https://www.bmwgm5.com/Logic7_E90_91_92_93.htm
http://www.e90post.com/forums/showth...hlight=dynavin

If the idrive screen is exposed, would it cause the radio to turn on and off?
The Ac/Dc fuse?
On mine the whole idrive screen is taken apart and i drive with it like that, but also the xdrive is throwing a code... so when i drive and hit a bump (the suspension is no bueno) the radio turns off and completely resets. Battery/fuses are ok.

xdrive sensor near bad suspension is ok

I read that the fuses on the back of the screen can cause issues as well, but everytime i put in a new screen/check it, nothing changes the issue