. . =3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D Aug 7, 2004, 12:37pm (CDT+5) From:
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 !!!!! =A0 mac =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
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 ~:~ =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D