Pioneer wont let me reprogram

I have an 02 chevy trailblazer, the check warning light just came on so I went to the dealership to get it checked out. The dealership said I needed to have my computer reprogramed, I told them to do it. they called back a few hours later and said they couldednt reprogram because the fuse in my Pioneer (AVX-P7300DVD) head unit would let them do it. they ended up taking the fuse out of the pioneer reprograming then puting the fuse back in and everything was fine. my question is why did this happen? have any of you had this happen? wat the unit improperly installed? thanks

I don't see how the radio had any effect on the vehicle computer unless who ever hooked it up did it wrong. There is not any wires, other then the one that goes to the parking brake that is unusual when hooking this up. Whoever hooked it up should have used the DCGM09 scosche wire harness. If they spliced into the vehicles wiring harness I would have it rechecked. There might be a data link wire to the stock radio. If this wire has been tapped into you are going to experience more problems in the near future.I may be lost but I am making good time.