HELP! Buick Tranny problem

Having a problem I need to get some info on. If anyone can give an answer, it would be much appreciated. Please reply via email as well as the boards, as my server doesn't keep a lot of messages, it seems.
2003 Buick Century 3.1L V6 with 4 spd automatic trans, 119,000 miles
Recently started shifting hard at times, not constant. When I had the oil changed last weekend I had the trans fluid changed as well. Started shifting harder, but again not constant. Yesterday on the way home, it started shifting extremely hard, shaking the car in 1-2-3 and banging into and out of 4th. Got it home and checked tranny fluid, it was a bit overfilled, but not incredibly so. Parked it for the nightand borrowed my daughter's car. Talked to a good friend who is a Jaguar Service Manager, he told me the controller (computer) may need reset, and recommended Lucas anti-slip additive as a temporary measure. He said the overfill on the hydraulic fluid wouldn't hurt anything. I did the computer reset, no change at all, just had to reset the clock and the presets on the radio. Took it back to the shop that did the fluid change when they opened this morning, they checked and agreed the fluid was high, drew out the excess and added the lucas in for me. No change, maybe a little softer shift, but after a 15 mile test drive it was back to square one. Also started noticing that when it downshifts from 2nd to 1st, the car feels like its on a bumpy road for just the time it takes to shift (which is 2-3 seconds since this started getting worse) Then the Service Engine Soon light came on, so on the way home from test driving, I stopped at Autozone and had them put their tester on it. Not sure of the code #, but it said "Torque Converter Circuit Stuck Open". ??? I called Jon (Jag man) andhe said he had never heard of this code but would look it up and let me know what he finds. I've Googled it a few different ways and can find nothing, and in the GM trouble codes, this verbage doesn't show up. I'll call the dealer on Monday,but in the meantime, wondering if anyone can shed some light on this? Could the trouble code be causing the slippage and hard shifting? Or the hard shifting and slipping cause the trouble code? Am I about to invest in a new or rebuilt tranny? The hopeful answer here is NO! Any help much appreciated
Marty mmontjoy at sc dot rr dot com
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I had to put in a new tranny on a 3100 V6 6 Cylinder @ about 135,000 miles, 4 speed auto with the overdrive.
I really don't think you need to have a new tranny, maybe, but i doubt it.
Why not take it to a BUICK Dealer? Might cost you $50 for an estimate, but adding some magic fluid isn't going to do a thing, i don't think.
good luck.
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snipped-for-privacy@yahoo.com wrote:

I'll be calling the dealer Monday, but as I noted, it's the weekend and I'm just trying to get some info in advance. But for reference, the anti-slip additives actually work quite well, when just wear and tear is the problem. Thanks
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It's a Pressure Control Solenoid problem.
GM knows about,
TSB #00-07-30-002B describes the problem
Lots of discussion on these links,
http://www.automotivehelper.com/topic179354.htm
http://www.automotiveforums.com/t399190.html
http://www.google.ca/search?hl=en&q=harsh+shifting+4t65e&meta
Rugburn wrote:

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Section: 07 - Transmission/Transaxle Bulletin No.: 0O-07-30-002B Date: July, 2002
Subject: Slips, Harsh Upshift or Garage Shifts, Launch Shudders, Flares, Erratic Shifts and Intermittent Concerns, DTC P1811 or P0748 Set (Replace Pressure Control Solenoid Valve Assembly)
Models: 1997-1999 Buick Riviera 1997-2002 Buick Park Avenue 1998-2002 Buick LeSabre 1999-2002 Buick Regal 2000-2002 Buick Century 2002 Buick Rendezvous 1997-2001 Chevrolet Lumina 1997-2002 Chevrolet Monte Carlo 1999-2002 Chevrolet Venture 2000-2002 Chevrolet Impala 1997-1999 Oldsmobile Eighty Eight 1997-2002 Oldsmobile Silhouette 1998-2002 Oldsmobile Intrigue 2001-2002 Oldsmobile Aurora (3.5L) 1997-2002 Pontiac Bonneville, Grand Prix 1999-2002 Pontiac Transport/Montana 2001-2002 Pontiac Aztek with Hydra-Matic 4T65-E (RPOs MN3, MN7, M15, M76)
Condition: Some owners of the above vehicles with a HydraMatic 4T65-E transaxle may comment on harsh upshifts or harsh garage shifts, soft shifts, shudders on hard acceleration, or shifts erratic. These conditions may appear intermittently or set a DTC P1811 or P0748. During diagnosis, a low or high line pressure (actual versus desired) may be observed.
Cause: The above condition may be due to any one of the following which may affect line pressure output:
Sediment inside the pressure control (PC) solenoid valve, causing the PC solenoid valve to mechanically bind. Sediment in the valve body, causing the torque signal regulator valve to stick. Incorrect transaxle oil level
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Thanks! I will be looking into this first thing Monday! Really appreciate it!
snipped-for-privacy@idirect.ca wrote:

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