Buick/Olds: 4T60E Transmission, torque converter clutch, vehicle speed sensor


Question
I own a 2001 Buick Regal LS (non-supercharged 3800) with the 4T60E Transmission.  It runs well and shifts smoothly, but starting the other day, I noticed a problem.  With the transmission selector in OD, on the highway, I believe the torque converter clutch is not locking in 4th gear.  If you  have the car on the freeway with the selector in 3, I believe it is locked (the tach only moves very slightly if pressure is removed from the accelerator).  But if you put the selector in OD, the engine will immedeatly drop to idle at 1,000 RPM on the freeway when accelerator is released.  I know these transmissions have problems with the TCC soleniod, but have you ever heard of it working in 3rd gear but not in 4th, and is it even possible?  I have always done all of my own auto work myself, are there any tests or procedures you can think of that may help pinpoint the problem.  I thought maybe vehicle speed sensor, but the OBD is not showing any codes.

Any info you can possibly give would be greatly appreciated!

-Zach

Answer
You are correct about the TCC solenoid problems but they also have problems with the pressure control solenoids. I dont know of any tests that you could do without having a TechII scanner to test and monitor all of the trans data. If it was the VSS you would also have problems with the speedo. Take it to the dealer to have it diagnosed. They should have lots or experience testing the components in your trans.