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Transmission Not Shifting


Full Member
Jan 2, 2003
I have 2003 Z-71 with about 3000 miles on it and have noticed something odd in the last few days. When I leave my driveway the roadway I enter is at about a 5% grade. If I go downhill I have noticed that the Transmission is not shifting unless I let off the gas momentarily then it will after that hesitation. If I don't lift it will get to 4000 to 4500 rpm before shifting. Fluid levels are all OK and this only seems to do it when I go downhill. If I turn the other direction when leaving my driveway (uphill) I haven't noticed the problem. Any Ideas?

Make sure the "TOW HAUL" is not engaged on your gearshift. It would be more apparent going downhill.
I have been experiencing the exact same thing with my '03 Z-71 since day one (~2mos. ago). It will shift from 1st to 2nd normally, but will shift from 2nd to 3rd only at an excessively high RPM, unless I back off the pedal considerably. I am possitive the truck is not in tow/haul mode. I have not been very concerned about it since (for me) it ONLY does this when I first leave home (downhill) AND the truck is cold. Any thoughts on this would be great.

Just a total shot in the dark here: Does the PCM change shift points for a period of time when the engine/tranny is cold, like it does when tow/haul is engaged? And in this setting AND going downhill, it's making some sort of mistake?

Check your owners manual. I remember reading in mine the tranny will shift different to help warm the engine to operating temp.
Shep that sounds exactly like what mine does. You just do a better job of explaining it than I do.
I have had trouble shifting from 1-2 in the Av after I put on a hypertech programmer, FPIK, and flowmaster 40. Before I put these on, the Av would not shift out of 2nd when the temp reached below zero. Does any body know whats wrong or have a similiar problem?