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

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

.
.
============Aug 7, 2004, 12:37pm (CDT+5) From:

macnews@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 ....

{a}
  Gone
{b}
  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
~:~
========================