4l60e
 

. I have 96 z71, my old trans went out bought a rebuilt one and put it in.. Here is the problem it will not shift into o/d on a great clear day. But let it be raining or the streets be wet and it will go into o/d.. It may stay in o/d and do fine or it may jump in and out.. Can anyone point me to a starting point..or give a idea where to start

Did you replace the torque convertor?????? that is where "lock up" happens....if you didnt then you wasted your time...also check all wires going to the tranny for chaffing or cuts.

yes i replaced the torque convertor..I have traced wiring until i,m blue in the face.. One of these days i will find the problem

I would just about bet it's an electrical connection breaking down somewhere. Often wet conditions may cause you to lose your connection but it could cause you to create one also. I would pull every plug apart and check for bent or pushed back pins, clean with contact cleaner and seal it up. You may want to put dielectric grease in the ones exposed to the weather. Good luck.