I just completed my 01 lm7/4l60e conversion and I'm having a shifting issue with my trans it shifts great for the 1-2 and 2-3 shifts even locks up at45-40 mph bit I have no 3-4 shift any ideas or suggestions? I rebuild the trans myself and have a few ideas of the cause I'm just trying to eleminate anything electrical before dropping the pan..

 

I just went trough this my self. a few months back I lost 4th. Fluid was fine, all other gears shifted perfect and at the right times. The PCM was comanding 4th apply but I was not seeing it. it just stayed in 3rd. NO signs of slipping components either. And because i had a proper 2nd gear, I narrowed it down to a bad 4th apply servo. The only difference between a 2nd and 4th gear shift is the servo. So if you do not have 4th, and only 4th with no other problems, then your 4th gear servo is fubar.

I pulled mine out last night and sure enough, my servo was seized. Put a stock one back in and all is perfect again... so now onto ordering new billet servos.

 

What did you use for the 4th gear servo? Also if you installed a transgo shift kit I would verify that you installed the 3-2 downshift valve spring in the correct location. I have seen guys get confused and install it in the 3-4 relay valve bore and not have 4th gear. I do not think that you have an electrical issue because you have first gear. The same solenoid used for 1st comes on in 4th as well. Vince