Help: 4L80E shifting problem(Mike L. Help!)

[Sandracer799]

The 4L80E I have started acting like the converter was going bad the other day. Like it was slipping. But upon further diagnoses it is not the converter. When you put the truck in first the truck goes great shifts through all the gears. When you put the truck in second, it will start out in 2nd like it is suppost to. (Aftermarket tranny controller)

However when I put the truck in OD the truck will sometimes start out in 2nd and sometimes start out in first. And if you give it half throttle or more the tranny doesnt know what to do and starts shifting back and forth violently causing the whole truck to shake.

I know there is a 1-2 shift solenoid. Could this be bad? Or is it something worse?

Thanks for the help!

 

[Mike L.]

Replace both shift solenoids first. Easy to do with a pan drop.

 

[Sandracer799]

Thank you I will try that.

 

[Sandracer799]

So I finally got around to replacing the solenoids this weekend. Same thing still.


My local transmission guy thinks it is something in the stand alone controller, but wont not say it is something wrong with the trans itself. TCI says it sounds like the 1-2 shift tables are to close together.

That just doesnt sound right to me. Because it has been working great for over a year and then all of a sudden it started doing this.


Any help or advice you could give me would be great!