C 1500 Truck 2WD V8-6.5L DSL Turbo VIN S (1997)
PROM - Programmable Read Only Memory: Customer Interest
A/T - Harsh 1-2 Upshift or Harsh Upshifts All Gears
File In Section: 7 - Transmission
Bulletin No.: 87-71-62
Date: May, 1998
Subject:
Harsh 1-2 Upshift or Harsh Upshifts All Gears
(Reprogram PCM/VCM)
Models:
1997-98 Chevrolet and GMC C/K, G, P Models
with 6.5L Diesel Engine ("VINs F, S, Y - RPOs L65, L56, L57) and HYDRA-MATIC 4L8OE Transmission (RPO MT1)
Condition
Some owners may comment on harsh transmission upshifts from first to second gear or harsh transmission upshifts in all gears.
Cause
Condition may be due to software calibration that allows the shift adapts to modify line pressure and maintain the maximum adaptable line pressure.
Correction
If normal diagnosis does not provide a correction, reprogram the PCM/VCM with the appropriate calibration listed.
Service Information
Do not attempt to order the software/calibrations from GMSPO. They are programmed into the vehicle's PCM/VCM via a Techline Tool Device.
