Aftermarket Radio Installation - BMW Forum

asamech1 · 05-10-2012, 11:52 PM

Hi all,
I am trying to install a aftermarket radio, a Kenwood 252u, and have gotten the after market wiring harness and antenna adapter. I have it all hooked up but have not sound. Every other feature seems to work fine. Also there are two other connectors on the back of the radio. One is a small adapter and the other is a multi prong shielded ground. What are these for and is there some reason I can not get sound that might be unique to BMW's. I have done installs before and never had this problem and since there are more wires on the after market connector than on the car harness I am confused.

jasonj · 05-16-2012, 10:25 AM

hi do the wires from the head unit have writing on them ground, 12v live, remote etc.. also how many wires is there from head unit? and how many wires to car harness? also do you have old head unit if so is there any codes on back if so please put them on here and il see if i can help

asamech1 · 05-16-2012, 08:52 PM

Thanks but I got it straight yesterday. The harness I used was color coded, red to red, green to green and so on. What is did not know is if your car has a amp it is not blue to blue, it is blue to blue and white.
Still do not know what the other two wire bundles are for. I think one is for the security and the other I do not know. Also I think the amp is in the trunk on the left side but when I looked for it I also found another box and have no clue what it is.

kwandrey · 09-10-2012, 01:09 PM

Hi I just went through the same thing in my 92 e32 735iL got the BMW adapter fillowed all the colors and also Blue to Blue/white. nothing. Looking closer at the wiring Red is switched 12V Yellow constant battery power. so played aronud and connected RED YELLOW and BLUE and IT works - Key switch off and radio is off removing the yellow on car side and power goes off to radio seems to need all 3 when all 3 get connected I get a few beeps and red flashes on the anti theft light near radio. Just curious if the factory radio CODE communicates back to power up maybe the yellow lead?
Seems odd and don't want to drain my battery having it hooked up like that.
I will put my meter on the yellow and red coming out of the body harness connector and see whats up.

It could be that I am not getting power out of the yellow body side connector but all fuses are good. Could it be that there is an inline fuse on that lead back by the battery?
We did notice the amp clips quite a bit if turned up past 19 on volume its a 45w Pioneer CD player Seems Okay if we turn down the EQ and don't use loudness.