4L60E Question? 3rd Gear

[mrchev]

1993 GMC 1500

Same problem after having rebuilt 2 years ago.  (it did this issue prior to rebuilding)

Guy was nice, but too long to get trans back during rebuild.  So, I've been driving it fine for now.  But question________

 

While I am accelerating (getting onto the freeway). 

First gear is fine

Shifts into Second Gear fine.

During shifting into 3rd gear, if rpms are above 2500-3000 or above.........the transmission jumps out of gear and revs.  Let off the gas and jumps back into gear and I proceed normally.  shifting onto 3rd under 2500 rpms it always works fine, no events whatsoever.  With cruise on, or pulling a load..........cruise on:  going up inclines and the trans has to downshift or going over 2500 rpm.....engine revs (comes out of gear) let off, jumps back in gear.  Pulling a load, (car trailer).  going up incline......acceleration anything over 2500-3000 pop out of gear.  let off and goes back into gear.

[richard wysong]

you need to use a scan tool that records the transmission operation to see what's causing that problem. any stored trans  codes?

[richard wysong]

hmm, 93 may not be electronic trans. do you know what trans you have?

[richard wysong]

never mind . I see the title of the post, 4L60E

[mrchev]

On 6/4/2022 at 6:04 PM, richard wysong said:

you need to use a scan tool that records the transmission operation to see what's causing that problem. any stored trans  codes?

 

something interesting.  I pulled it back into drive rather than overdrive.  Accelerate getting on freeway and it shifts fine into 3rd gear.  But doing the same thing in overdrive, it jumps out of gear at around 3K.  So, the problem doesn't appear in drive. Afterward, I can shift in overdrive and all is well.

[richard wysong]

it sounds like you may have an internal hydraulic leak providing the fluid levels up. have you scanned it to make sure the shift solenoids are ok?