2002 Yukon XL Factory Amp?

Evening folks, and thx in advance! I have a 2002 Yukon XL that I've just upgrade the audio system. Which consist of 3amps(1 for each 12' sub, and 1 for my mids and highs), & a new Kenwood DDX-7017. I have a couple of problems... 1, sometimes when i start my vehicle, the front & rear speakers wont play unless of switch my engine off and on, or I can pull the fuse for ONSTAR and re-insert it which will allow the speaker to play again. 2, now that I have an amp on the factory speakers(I chose not to re-wire), when I turn the volume up past a certain point, the front and rear speakers "clip" as if there is another in line amp somewhere. WTF is goin on? Does my vehicle have a factory amp installed somewhere?? If so, where would it be & how would I bypass it??

It's under the seat.  There is a bypass harness available, otherwise you can just run wire from your new deck to the amp and "pop" the speakers.  This is explained under the sticky "how to figure out stereo wiring".My ex once told me I have a perfect face for radio.

I just ran all new speaker wire and replaced the speakers in my 2002 Yukon. It wasn't all that hard, just time consuming. If you have any specific questions about it let me know. -Scott 2002 GMC Yukon SLT non-Bose

Pioneer AVIC N3