[Chigga]

Originally Posted by ctuna

Step one there is either power to the Radio or not
Radio has a fuse on the back and one in the cabin fuse panel.
If you have a low battery the IBS may be turning off power
to the Radio.
If you have done the above checks and there is power on the
Radio connector and it doesn't turn on then its the radio.

IBS system can turn accessory's such as the Radio off if it
detects a low battery or is defective.
Read first pdf

electical e90 pdf
http://www.google.com/url?sa=t&rct=j...,d.cGU&cad=rja
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU
http://www.google.com/url?sa=t&rct=j...85464276,d.cGU

Ctuna, I did all that on a 2006 323i, but the radio still refuse to power on.

- Had new battery, coded.
- The lights come on around the stereo,chime works etc.

But the radio just won't power on, even swap out to another known working unit, still won't power on, then bought the aftermarket harness and swap it to an aftermarket head unit that was working, it's not powering on, so I'm bit at loss here, why wouldn't it power on? I check all the fuses and everything seems fine, I just can't get 12v power to the headunit.

Any help would be great.

[ctuna]

Follow the Voltage. There should be 12 Volts at the Radio Fuse behind
the glove compartment.(on one side of the fuse with the fuse pulled and at the back of
the radio harness with a good fuse in place)
Also you should have zero ohm between the Radio Harness 12 volt line and
from one side of the fues to the radio harness 12 volt pin.

Are you trying to put the factory unit back in or install something new?
Is it the stock harness that is having trouble with the stock radio?

[Chigga]

Originally Posted by ctuna

Follow the Voltage. There should be 12 Volts at the Radio Fuse behind
the glove compartment.(on one side of the fuse with the fuse pulled and at the back of
the radio harness with a good fuse in place)
Also you should have zero ohm between the Radio Harness 12 volt line and
from one side of the fues to the radio harness 12 volt pin.

Are you trying to put the factory unit back in or install something new?
Is it the stock harness that is having trouble with the stock radio?

Hi ctuna.

Got the car couple months ago that needed TLC, sorted out everything except now just the stereo, all the fuses on the board has been replaced with new ones.

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.

[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

[alz.s7]

I've had the same problem with my radio on my lci e92, it just randomly stopped working and is now blank. I've tried to buy and fit and new radio but this still hasn't fixed it. Could this be a fuse and what one would it be? Ive also tried the fuse behind the radio and some others in the glove box.

[ctuna]

https://www.google.com/url?sa=t&rct=...,d.cGU&cad=rja

You need to measure the voltage on the line that feeds the Head Unit and follow it back.
BMW diagnostics like Inpa and Ista D would help.

[Bmwguyosk]

Edit: I have solved/fixed the problem

The problem of having no power to the fuses that power the radio-
The fix for me was - if replacing the fuse box to a new one,
Dont forget these 2 fuses. (Pic in attachment) zoom in!
Black lookin fuses deep in the fuse box.

Originally Posted by ctuna

https://www.google.com/url?sa=t&rct=...,d.cGU&cad=rja

You need to measure the voltage on the line that feeds the Head Unit and follow it back.
BMW diagnostics like Inpa and Ista D would help.

Im doing some diagnostic on my brothers 328xi 2009 e90
Car had no power what so ever.
Replaced ground strap under front wheel(was completely broken)
Replaced b+ wire and fuse box.

Car works mostly

Now the radio wont turn on. Most fuses are 12v+, but no 12v to the fuses that supply to the HU (tested connector behind HU and fuses) im getting 353mV back there

Tried with and without Ibs plugged in

everything else is working

Still no luck. Whats next in line to the HU power connector, is it directly to the fuse 14?
The fuses are not showing 12v

Thanks ahead of time if you take the time to read this^^

Oh, i also have Ista + , inpa, multimeters, and so on.

[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