Harsh 1-2 Shifts (Reflash PCM Calibrations)
| Subject: | Harsh 1-2 Shifts (Reflash PCM Calibrations) |
| Models: | 1999 Chevrolet and GMC C/K Models (Silverado and Sierra) |
| -- with 4.8L, 5.3L , or 6.0L Engine (VINs V, T, U -- RPOs LR4, LM7 LQ4) and HYDRA-MATIC 4L60-E or 4L80-E Automatic Transmission (RPOs M30, MT1) |
Condition
Some owners may comment on a harsh 1-2 shift.
Cause
Condition may be caused by insufficient line pressure under heavy throttle.
Correction
Reflash the Powertrain Control Module (PCM) with updated calibration to soften shift. These calibrations are available on 1998 CD-ROM #20 and later versions. Refer to your Service Manual for proper procedure.
Engine and Transmission | New Calibration Number | Previous Calibration Number | Axle | Application |
|---|---|---|---|---|
6.0L\4L80-E | 16264187 | 16253293 | 3.73 | CK200 |
6.0L\4L80-E | 16264188 | 16253294 | 4.10 | CK200, Calif |
6.0L\4L80-E | 16264205 | 16264138 | 4.10 | CK200, Europ |
6.0L\4L80-E | 16264206 | 16264140 | 4.10 | CK200 Exp PB |
4.8L\4L60-E | 16264165 | 16254164 | 3.42 | CK100 |
4.8L\4L60-E | 16264167 | 16254166 | 3.73 | CK100 |
4.8L\4L60-E | 16264243 | 16264200 | 4.10 | CK100 |
5.3L\4L60-E | 16264244 | 16264201 | 3.42 | C100, 200 |
5.3L\4L60-E | 16264245 | 16254202 | 3.73 | C100, 200 |
5.3L\4L60-E | 16264246 | 16264203 | 4.10 | C100, 200 |
Warranty Information
For vehicles repaired under warranty, use:
Labor Operation | Description | Labor Time |
|---|---|---|
J6355 | Prom - Reprogramming On Car | Use published labor operation time |
