4l60e problems

chevrolet
suburban
transmissions

#1

I have been helping a friend with problems on a 1999 Chevrolet Suburban, 4L60e, 2WD and we are at loss as to what is wrong.



It will not shift beyond 2nd gear. Reverse still works. No problems with the speedometer.



The pressure switch manifold was replaced. The solenoids were checked and are fine. We even tried replacing the speed sensor, but there was no change.



Other chat rooms/forums have posts about this problem with 4L60e’s, but no one seems to have an answer. Many people have replaced the transmission but the problem still persists.



Any ideas as to what we should look for next before replacing the transmission?


#2

Have you had the transmission control module scanned for codes? If you only have reverse and second gear, i.e. no 1-2 shift, the TCM is in limp home mode.

Get back to us with any codes you have found. Maybe by that time Transman618 will have responded because he is ‘the expert’ on these transmissions and control systems.


#3

Ok, so its shifting from 1st to 2nd… What happens next, does it just wind out in 2nd or soes it neutral out when it should hit 3rd?? A very common problem in these transmissions is a weak 3-4 clutch assy. EVERY one of these that cross my bench get new updated 3-4’s. How many miles are on your Sub??

transman


#4

It winds out after hitting second. It has 120,000 miles.


#5

We had the onboard computer scanned. There were no codes. We do have first and second gear.


#6

Ok, what you need to do next is connect a scanner. This is going to take a high end scanner, something that will monitor live transmission data. We need to know whether the computer is commanding 3rd gear.

transman