2003 Tahoe Z71 5.3 will not shift from second. I had transmission repaired ($1500) Next day I got no shift problems. I had tps/pps codes and no shift from second. i reset ecm & pulled red plastic lock from top of connection block @ pps & cycled (koeo) pedal full up to full down and then reconnected plastic lock. Now have no codes but still will not shift. What can I do , or have I done too much already?