CHUGGLE / SURGE ON TCC APPLY NO DTC'S - REFLASH PCM. GMC Truck Savana 1997

REVISION: 04/09/97

THIS BULLETIN IS BEING REVISED TO ADD AN IMPORTANT STATEMENT.

SUBJECT: CHUGGLE/SURGE ON TCC APPLY/NO DTC'S (REFLASH PCM)

MODELS: 1996-97 CHEVROLET AND GMC C/K AND G MODELS WITH 5.7L ENGINE (VIN R - RPO L31) AND HYDRA-MATIC 4L60-E TRANSMISSION (RPO M30)

CONDITION:

SOME OWNERS OF THE ABOVE MODELS MAY EXPERIENCE A CHUGGLE/SURGE WHEN TCC IS APPLIED UNDER LIGHT THROTTLE ACCELERATION.

CAUSE:

ENGINE INPUTS (COMBUSTION EVENTS) EXCITING THE VEHICLE PLATFORM/DRIVELINE OR TIRE BALANCE MAY BE A CONTRIBUTING FACTOR.

CORRECTION:

FIRST ENSURE THE MOST RECENT ENGINE, NOT TRANSMISSION CALIBRATION HAS BEEN INSTALLED (CORP. #76-65-04) AND CHECK TIRE BALANCE.

A NEW TRANSMISSION CALIBRATION TO CORRECT CHUGGLE/SURGE IS AVAILABLE FOR USE ON VEHICLES WITH PERSISTENT CONCERNS ONLY.

IMPORTANT: THIS CALIBRATION WILL RAISE TCC ENGAGEMENT APPROXIMATELY 7-10 MPH DEPENDING ON APPLICATION. THIS CALIBRATION SHOULD NOT BE INSTALLED UNTIL THE ENGINE CALIBRATION LISTED ABOVE HAS BEEN INSTALLED. INSTALLATION OF THIS CALIBRATION MAY LEAD TO DECREASED FUEL ECONOMY DUE TO TCC ENGAGEMENT AT HIGHER SPEEDS.

REFLASH THE POWERTRAIN CONTROL MODULE WITH THE APPROPRIATE PART NUMBERS BELOW.

REFER TO YOUR SERVICE MANUAL FOR PROPER PROCEDURE.

SERVICE PARTS INFORMATION

1996 TRANSMISSION CALIBRATIONS

CURRENT NEW FILE # FILE # VERSION

16227574 16227607 CD ROM 1997 DISC 4 16227575 16227608 CD ROM 1997 DISC 4 16227576 16227609 CD ROM 1997 DISC 4

1997 TRANSMISSION CALIBRATIONS

CURRENT NEW FILE # FILE # VERSION

16243558 16243589 CD ROM 1997 DISC 4 16243560 16256440 CD ROM 1997 DISC 4 16243561 16256441 CD ROM 1997 DISC 4

THIS NEW CALIBRATION WILL BE AVAILABLE STARTING WITH THE 1997 DISC 4 UPDATE.

WARRANTY INFORMATION:

FOR VEHICLES REPAIRED UNDER WARRANTY, USE: LABOR CODE: J6355 REFLASH CONTROL MODULE

USE PUBLISHED LABOR OPERATION TIME.

FIGURES: 0 ATTACHMENTS: 0

GENERAL MOTORS BULLETINS ARE INTENDED FOR USE BY PROFESSIONAL TECHNICIANS, NOT A "DO-IT-YOURSELFER". THEY ARE WRITTEN TO INFORM THOSE TECHNICIANS OF CONDITIONS THAT MAY OCCUR ON SOME VEHICLES, OR TO PROVIDE INFORMATION THAT COULD ASSIST IN THE PROPER SERVICE OF A VEHICLE. PROPERLY TRAINED TECHNICIANS HAVE THE EQUIPMENT, TOOLS, SAFETY INSTRUCTIONS AND KNOW-HOW TO DO A JOB PROPERLY AND SAFELY. IF A CONDITION IS DESCRIBED, DO NOT ASSUME THAT THE BULLETIN APPLIES TO YOUR VEHICLE, OR THAT YOUR VEHICLE WILL HAVE THAT CONDITION. SEE A GENERAL MOTORS DEALER SERVICING YOUR BRAND OF GENERAL MOTORS VEHICLE FOR INFORMATION ON WHETHER YOUR VEHICLE MAY BENEFIT FROM THE INFORMATION.