I've rebuilt this 95 4l60e in my friends truck for him. I have no 1st or 4th. I've done all the tests and have checked computer, power, 1/2,2/3 solenoids, wires, swapped solenoids,have power to E terminal, even went as far as manually ground 1/2 solenoid and that will fire off and gives me 1st and 4th. Unplug computer and replug it and will start in first but as soon as shifts won't get It again and won't get 4th. Only code is 66 which is 3/2 solenoid. Will that put tranny in limp? Shifts buetifully when it does shift. Have done continuity on wires to computer and reads good. Start in second and Upshifts to 3rd then nothing else. Can pressure solenoid cause this if bad? Sorry if sounds like I'm rambling but brain is a
shot! Help please. Got on here because I was reading some good info from someone I think named Allan. Thanks.

 

I also have this problem with my 95 Chevy Silverado and can not determine what it is. Replaced computer, ignition harness, checked all my grounds and everything. I want to say it’s definitely electrical but I’m not sure where.