So I have a 2003 single cab short bed silverado with the 4L60E It has been shifting perfect never low on fluid and it doesnt smell burnt, but one morning it wont go in third. It will drive and has power in first and second but in third or drive its slipping. I suspect its burnt up but, I have been doing a little research and it sounds like it shifts by selinoid. Is that true? Is it possible That a bad selinoid is the problem? How can I find out? Thanks

 

ohh I also found that when I started getting this problem the tow/haul button quit working dont know if that could be part of it.

 

I am basically answering the same question in this thread today:

https://ls1tech.com/forums/automatic...-question.html

If it feels like it has some acceleration in 3rd gear, the 3-4 clutch is likely slipping. If it feels like neutral after the shift out of 2nd, it might be Shift solenoid "B".

 

thanks ill investigate more