Swap alpine amp with Lear

[haydenswitzer]

The Alpine HiFi amp on my 2005 x5 3.0i recently went out and I went to a junkyard today to find a new one. I ended up finding the Lear E39/E53 DSP amp along with the sub that comes with that model. I tried to put it into my car only to find that the Alpine amp connection is not the same as the Lear.

Further into the trunk under the spare I did find the 2 connectors that fit into the Lear amp. I hooked the amp up and did not get any audio out of any of my speakers, but instead the fasten seatbelt warning kept dinging and my air conditioning came out hot. I disconnected the amp and everything went back to normal. I also did not find any cable to hook up the sub

I have an aftermarket stereo that my buddy installed and that may be the reason why the speakers did not work but I am not entirely sure. The stereo was put in after the amp had blown (when I brought my car to the audio shop the guy said there was no amp in my car and the stereo needed to be replaced) and he may have not installed it correctly.

Is there any easy way to connect this amp to the car? And is there any way I can hook up the sub as well? I was thinking if BMW took the time to put the amp connection in there would be an easy way to hook up this amp and most likely the sub