LS1MCSS

iTrader: (18)

I have an 03 4L60E that has 1st, 2nd, and reverse. No 3rd or OD. Any idea what might have gone wrong? It belongs to my son and I'm not sure if made any noise when/before it started this or not.

mrvedit

Its the most common problem reported with the 4L60E - the 3/4 clutch is toast.
Based on your short description, the trans will need to be pulled and rebuilt.
Either have your local shop rebuilt it with a minimum 7-friction 4L65E clutch kit, or consider purchasing a performance rebuild from one of the sponsors here (Performabuilt, RPM or FLT).

There are similar threads this week, even today:
https://ls1tech.com/forums/automatic...n-problem.html
https://ls1tech.com/forums/automatic...e-rebuild.html

And a bit older:
https://ls1tech.com/forums/automatic...gear-gone.html

The symptom is that on the 2-3 shift the engine rpm climbs rapidly with little or acceleration of the car. Please confirm that to be sure this is the problem.

performabuilt

iTrader: (25)

Agreed sounds like the 3-4 clutch set is toast time for a new one or a rebuild.

LS1MCSS

iTrader: (18)

I'll tear into it in a couple of weeks and let you know what happened to it.

mrvedit

You might want to subscribe to this very similar current thread:

https://ls1tech.com/forums/automatic...n-problem.html