1. Fluid level okay while running, warm, level surface.------YES
1a. Fluid color and smell------YES
2. Speedometer reading correctly------YES
3. Shifting normal/hard-YES
4. Shifting into OD okay?-YESS
5. Any service engine light: /no
6. If SES light on, what codes do you have?
7. Model year: 1993
8. Describe symptoms: Slipping in 4th gear.
9. Does the engine come up to full temperature? YES
10. Any service work recently done that may contribute to your issues.
11. Does the TCC lock up (or how many "shifts" do you hear?)
12. Are you experiencing any kind of slipping? YES
13. What type of rear do you have? (Check RPO codes) 4.10
14. If you have an accurate tachometer, what is the RPM at 55 or 65?

I am having problems with the overdrive in my transmission. It shifts fine 1-2, 2-3, and 3-4 but as soon as it shifts into 4th gear the rpms rise and the mph falls off drastically like its slipping or some sort of fluid bypass? I have no idea what could be causing this so any help would be greatly appreciated.
Thanks
Joey

What does the fluid look and smell like?

Gary

The fluid looks and smells fine, Its like the gear applys then the fluid or solenoid bleeds off and allows it to start slipping.

Does it feel like it's shifting into 4th or does it feel like it shifted into neutral?

Does it feel like it's shifting into 4th or does it feel like it shifted into neutral?

It shifts into 4th but a couple seconds afterwards the rpm's start going up and the mph drops off. It still pulls, but acts like it is slipping.

You are going to have to pull codes.

Have you had this kind of trouble before?

Has anyone done anything to this truck before?

Take off the transmission pass through connector and examine it closely. Inspect it for oil, bent pins, pushed pins Male and female.

I am wondering if enough line pressure is getting to the Torque converter to cause mechanical lockup like it is supposed to.