4L80E Transmission Acting Up

[jtex]

Good Day,
I am having a bit of transmission trouble. I am running a 94, 6.5 on a 4L80E. 175,000 miles on both. Last week for no reason at all the transmission was stuck in 2nd gear. A key on and off fixed it for a while. After making a complete stop it would stay in 2nd. Key on and off and resume normal. No codes were set. I reviewed posts, removed and cleaned VSS front and rear, removed the wire bundle and clean, added dielectric grease to all. Same problems occurred with key on and off sometimes resolving the issue. Today, I removed and clean connections again. Still stuck in second. Hooked up the GMTD scan tech and took it for a spin. I can force it into 3rd and 4th using the computer. The TCC does not appear to be engaging. When I shift into reverse the Trans “clunks.” When I shift into 1st the Trans seems to bind up. A lot of throttle will move it but it is still binding. Am I relegated to a rebuild or am I missing something?
Today I found codes, 85 and 86 "ratio errors"

[Robyn]

This could be the end of the road and time for a rebuild.
I am however suspect that you may have a solenoid/S that are sticking.
Yank the pan down and clean it all out and see if there is a lot of crap in there.

If there is minimal junk in the pan I would try a fresh set of noids and see if that fixes the issue.'
If a solenoid sticks in its bore all sorts of wierd stuff happens.
The 4L is also noted for having high mile issues with the valve body.

These are aluminum and the bores wear over time and valves will stick causing all sorts of troubles.
The pressure regulator is also a possibility

The valve body is best fixed by replacing it as a unit (new part)

Give it a look see and go from there.
If there are no codes then this is a good thing. The scanner will not detect mechanical issues other than possibly low pressure stuff.

Hope this helps

Robyn

[Robyn]

This could be the end of the road and time for a rebuild.
I am however suspect that you may have a solenoid/S that are sticking.
Yank the pan down and clean it all out and see if there is a lot of crap in there.

If there is minimal junk in the pan I would try a fresh set of noids and see if that fixes the issue.'
If a solenoid sticks in its bore all sorts of wierd stuff happens.
The 4L is also noted for having high mile issues with the valve body.

These are aluminum and the bores wear over time and valves will stick causing all sorts of troubles.
The pressure regulator is also a possibility

The valve body is best fixed by replacing it as a unit (new part)

Give it a look see and go from there.
If there are no codes then this is a good thing. The scanner will not detect mechanical issues other than possibly low pressure stuff.

Hope this helps

Robyn