Is it possible to clear the codes and or dash display codes on a 2005 Chevy Tahoe without a scan tool. For example, turn key position to on, but not start, leave battery charger on and set for 10 minutes? Thanks 
Disconnect the battery. If the problem gets fixed but you don’t erase the codes, you won’t get a warning light after two or three drive cycles. Then the code will be erased in 80 drive cycles without doing anything else. If you just erase the codes without doing the repair, you could get a warning light within two drive cycles.
Yes, sort of. What you can do is you can disconnect the positive battery cable for ten minutes. The car’s computer will reset to the original settings. It will take two seperate twenty minute trips for the car to figure out what’s wrong again. That won’t fix the problem, though.
And, just to add, the car will probably find the problem and turn the light back on before it is ‘emissions-ready’. If your trying to sneak around the problem to past emissions, this probably will not work.