[ctuna]

Its known that if the head unit is missing
that this is true. There computer/repair is to dumb to ignore the lack of the original configuration .
If the amp is a L7 I can kind of see how that might be possible, since there is more communication than just audio.
By the way what is the issue?
The coding board setup can bypass some of this stuff as its
more basic in the way it works, but the dealership won't use
that.
if you still have it maybe you could plug the L7 back in temporarily.
You probably wouldn't have to hook it back up to the speakers.
Possible solution have them program the radio to Hi Fi
remove the L7 from the Most loop then program, just a guess.