4L60E Shift pattern is 1-2-1-2

[SubXero0]

You really need to stick a scan tool on there to see what the transmission is doing before going any further but it seems like your 3-4 pack is burnt.

When the band is applied you will have either 2nd or 4th. The only difference is whether the 3-4 pack is also applied and holding. If the 3-4 pack and band are applied along with the forward clutch you have fourth gear. If the 3-4 pack isnt holding but band is applied, you will have second gear. So if your scan tool shows that the pcm is commanding a shift into third from second but you're not mechanically shifting into third then that 3-4 pack is wiped and trans has to come out.

95% of all 4L60Es come in for overhaul due to the loss/burn up of the 3-4 clutch pack.

Ill get one hooked up as soon as I can, I know these transmissions love to blow up so Im suspecting its gone just want to make sure. thank you both for your help

 

[HotrodZ06]

I can almost guarantee it will need 3-4 clutches replaced. I would get a factory unit repair manual (it is a factory service manual for repairing transmissions and transfer cases) for the year of your truck if possible, if not as close to as you can. They are usually on ebay for a decent price and it will have exact procedures for rebuilding your 4L60E. I rebuild a lot of 4l60E's and they are not hard and will function perfect if you follow the unit repair manual. A used transmission is a huge gamble and may not last long if it does work depending on its history. If you choose to have someone else do the work make sure they aren't band aiding transmissions selling it as a rebuild, I have seen too much of that in my area. The best of luck to you fixing your problem, wish I could be of more help.

 

[NickTransmissions]

A used transmission is a huge gamble and may not last long if it does work depending on its history.

I rebuild a lot of "used" 4L60Es and most of them lasted six months or less for the individuals buying them before crapping out.

His 3-4s are most certainly wiped, though it took a little time to get a clear picture of the symptoms. Most folks initially tell you that it doesnt shift into 3rd (from their point of view there's no upshift) when in reality it is upshifting like it's supposed to from a command/control perspective but immediately neturalizing becuase the 3-4s are shot so it's really in first gear, mechanically. Unless you're familiar with transmissions that distinction isnt considered.

Like you said, there's a few key things to do on overhaul to make a 4L60E reliable and a few more things to get it to handle power and rpms, within reason.