Technical - Harsh 1-2 and 3-2 Shifts (Reprogram PCM)
| Subject: | Harsh 1-2 and 3-2 Shifts (Reprogram PCM) |
| Models: | 1999 Chevrolet and GMC C/K Models (Silverado and Sierra) |
| with 4.8 L or 5.3 L Engine (VINs V, T -- RPOs LR4, LM7) |
| and Hydra-Matic 4L60-E Transmission (RPO M30) |
Condition
Some customers may comment about a harsh 1-2 upshift during acceleration at light to moderate throttle opening. It is characterized by a "Bump" at the end of the shift. A similar condition may exist during a "Power-on" 3-2 downshift.
Cause
Condition may be caused by insufficient line pressure to complete the shift caused by component variation.
Correction
Reprogram the Powertrain Control Module (PCM) with the calibrations listed in this bulletin.
Parts Information
Engine and Transmission | New Calibration Number | Previous Calibration Number | Axle | Application |
|---|---|---|---|---|
4.8 L/4L60-E | 16264156 | 16264165 | 3.42 | C100 |
4.8 L/4L60-E | 16264177 | 16264167 | 3.73 | CK100 |
4.8 L/4L60-E | 16264210 | 16264243 | 4.10 | K100 |
5.3 L/4L60-E | 16264211 | 16264244 | 3.42 | C100/200 |
5.3 L/4L60-E | 16264212 | 16264245 | 3.73 | C100/200, K100 |
5.3 L/4L60-E | 16264223 | 16264246 | 4.10 | C200, K100 |
The calibrations listed are electronic calibrations and are NOT available from GMSPO. Calibrations will be available from Techline starting April 1999, on the 1999 Disk 10 CD ROM.
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation | Labor Description | Labor Time |
|---|---|---|
J6355 | PROM Reprogramming | Use Published Labor Time |
