What about the second question he had: "Will the computer retard the timing to prevent knock even if I have the timing advanced too much?"

Yep, I did not have the key turned on to the start position, just on to the accessory position. Worked like a charm after that. Thanks.

Okay, I give up.

I installed a brand new, ready to go, 1000 amp Auto Zone battery, topped it off with a smart charger for over an hour until the charger said "Full", pulled the three fuses, (even though I do not have OnStar), set the parking brake, disabled the interior lights, dimmed the dash ...

The factory battery is about two years old. I will try swapping in a brand new 1000 amp battery and see if that works. Thanks.

I was able to save the factory tune just fine, but when I try to install a custom tune or reinstall factory tune, I get the same error codes as the dude above. I charged the battery to full, left the charger on 2 amp trickle, and even removed the three radio fuses, (even though I do not have OnStar ...

I find this answer puzzling. On my 2005 Silverado, I changed from ~30.5 inch diameter stock tires (P245/75/16) to ~32.8 inch diameter tires (P285/75/16), and experienced no ABS problems. Also, a new tire can wear down an inch in diameter, or more, without triggering ABS fault codes. Is the 2006 ABS ...