PCM - Recalibration for Jerking Motion Symptom

File In Section: 06 - Engine/Propulsion System

Bulletin No.: 01-06-04-041

Date: August, 2001

TECHNICAL

Subject:
Vehicle Jerking Motion at Speed of 113 km/h or 70 mph
(Reprogram PCM For Correct Speedometer Calibration)

Models:
2001 Chevrolet and GMC G-Van Models
with 5.7 L Engine (VIN R - RPO L31) and SEO 9B9 (Electronic Speed Sensor)

Important:
"IPC" dealers are not authorized to utilize this service bulletin.

Condition

Some customers may comment on a jerking sensation when the vehicle reaches 113 km/h (70 mph).

Cause

Special Equipment Option (SEQ) 9B9, available only to fleets, was intended to limit the vehicle speed at 113 km/h (70 mph) through a mechanical road speed governor. However, for 2001 models, the speedometer calibration incorrectly shuts the fuel off at 113 km/h (70 mph) prior to the mechanical governor engaging This abrupt fuel shut-off/on may cause the vehicle to jerk.

Correction

The powertrain control module (PCM) must be reprogrammed with a calibration that does not include the 113 km/h (70 mph) limit. The new calibration will instead allow the road speed governor to smoothly limit the speed to 113 km/h (70 mph).