2000 Silverado 2500 4L80-E shift problems

I am having shifting issues with my recently purchased used 2000 2500 Silverado 4L80-E tranny. 94000 miles
It up/down shifts hard from gear to gear, it is intermittent, it is
usually when warm, no check engine light ever. It is sometimes a very severe harsh shift, and sometimes it shifts fine.
I just did this stuff yesterday to the tranny below....
Changed filter with a new GM tranny filter.
Changed 6 quarts of fluid, fluid and pan were pretty clean, I suspect previous owner did powerflush recently.
Changed the Pressure Control Solenoid in the bottom of the valve body, cleaned out the passages in the PCS area, tightened up the valve body-which was tight. Reassembled, and tested.
I only drove it a few miles since all that yesterday but still felt some shifting issues.
Any help here, can this be programmed or need software updates to the PCM?????
HELP !!!!! mac
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mac wrote:

This is the only item I can find for the 4L80 in that year: It doesn't appear to be the same problem you are describing, but it wouldn't hurt to have the latest calibration anyway. Have you ever had the vehicle checked for the latest calibrations?
Stall/Surge at Stop or Shifting to Drive/Reverse (Install Updated Calibration) #00-07-30-006 - (May 3, 2000) Stalls/Surge at Stop or When Shifted to Drive or Reverse (Install Updated Calibration) 1998-2000 Chevrolet and GMC C/K Models and G Van
with Hydra-Matic 4L80-E Transmission (RPO MT1)
This bulletin is being revised to include additional model years and new Correction information. Please discard Corporate Bulletin Number 87-71-63 (Section 7 -- Transmission/Transaxle).
Condition Some owners may comment on an engine stall or a slight surge at a stop or when the transmission is shifted into drive or reverse.
Cause The transmission calibration may not be optimal for the best engine/transmission performance.
Correction Install the latest new calibration.
Ian
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what is the average cost for this service at most dealerships? I went to the website where you enter your VIN and it checks for updates some time ago and it said I needed new calibration.
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David Norris wrote:

They may charge you up to an hour for this. I think that's a bit steep, considering it takes all of 10 minutes to do, but that's flat rate. I'm still very surprised that GM doesn't do software updates for free. Maybe, eventually, they will be forced to do this.
Ian
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thanks for your reply. Perhaps at some time in the future the more computer literate of us could download the patch and flash it with a laptop and a cable end.
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Hi Mac,
Have you found a solution to your problem yet? I am exeriencing the same thing with my 2500HD. I would appreciate hearing about it.
Thanks. Walter

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It has improved a little, I need to drive it with higher tranny temperatures to make sure, it wasnt to hot up in boston this weekend.
It does seem better. I hope its not the bands slipping and the tranny compensating with increased pressure, I seemed to have gotten ripped off by this truck I purchased online from the south recently.
How much is a gm factory rebuilt tranny 4L80-e for a 2000 cost these days, I will take those over any tranny shop rebuild, from my old Th700R4 in my 88 silverado
Walter wrote:

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. . ======= ======= Aug 7, 2004, 12:37pm (CDT+5) From:
snipped-for-privacy@billymac.net (mac) wrote in message:
I am having shifting issues with my recently purchased used 2000 2500 Silverado 4L80-E tranny. 94000 miles
It up/down shifts hard from gear to gear, it is intermittent, it is usually when warm, no check engine light ever. It is sometimes a very severe harsh shift, and sometimes it shifts fine.
I just did this stuff yesterday to the tranny below....
Changed filter with a new GM tranny filter. Changed 6 quarts of fluid, fluid and pan were pretty clean, I suspect previous owner did powerflush recently.
Changed the Pressure Control Solenoid in the bottom of the valve body, cleaned out the passages in the PCS area, tightened up the valve body-which was tight. Reassembled, and tested.
I only drove it a few miles since all that yesterday but still felt some shifting issues.
Any help here, can this be programmed or need software updates to the PCM?????
HELP !!!!! mac ========== ==========
MAKE SURE THE TRANNY IS GOOD AND HOT......THEN......
1) Pull codes on the computer, and write the codes down for posting here.
2) Clear the codes from memory, also pull the negative battery cable for a minute or two.....test drive the truck and see if the symptom was ....
Gone Improved (c) A different symptom showed up. (slipping)
Post the results.
It would be a sound idea to clear the codes then immediately pull codes again before the test drive to see if there is a hard failure.
Test #2 will indicate if the computer is initially commanding high line preasure from start. Clearing codes will also clear "learned" memory, and in so doing, will reset the system to factory programming. If the the harsh shift situation goes away for the first few stop and go's on a test drive, then you can perty much eliminate a computer programming and MOST components on the transmission as a cause. (not all....most)
If the computer thinks that the truck is being driven under a load situation... it will cause this symptom.
The most common sensors to cause this symptom, outside the tranny, are....
VSS TPS MAP sensor
in that order.
MarshMonster ~:~ ============= =============
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A quick update, This tuesday the tranny was acting up on my ride to work, harsh shifting through the upshifts. tranny temp was around 180
Wednesday,same trip to work, ran much better, a few harsh shifts here and there.
I hooked up Wednesday morning an OBDII unit with my PC Laptop www.obddiagnostics.com and there is no codes stored, no freeze frame data, nothing !!
I didnt try anything else because there are no codes, I reset the PCM anyway through the laptop. I am wondering if my PCM has issues ??
Marsh Monster wrote:

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