UNDESIRED TRANS.DOWN SHIFTING BET. 3RD & 2ND GEAR. GMC Truck Savana 1997

SUBJECT: UNDESIRED TRANSMISSION DOWN SHIFTING BETWEEN THIRD AND SECOND GEAR WHEN MANUALLY SHIFTED TO FIRST GEAR (D1) (NEW CALIBRATION)

MODELS: 1997 CHEVROLET AND GMC G MODELS WITH 4.3L ENGINE (VIN W - RPO L35) AND A HYDRA-MATIC 4L80E AUTOMATIC TRANSMISSION (RPO MT1) ON VEHICLES BUILT FROM S.O.P. THROUGH VIN V1018583

CONDITION:

SOME OWNERS MAY COMMENT ON A CONDITION IN WHICH A DESIRED DOWNSHIFT BETWEEN THIRD AND SECOND GEAR DOES NOT OCCUR UNTIL APPROXIMATELY 40 MPH (64 KMPH) WHEN SHIFTED MANUALLY INTO FIRST GEAR (D1).

CAUSE:

SOME VEHICLES WERE BUILT WITH AN IMPROPER TRANSMISSION DOWNSHIFT SPEED CALIBRATION WHEN MANUALLY SHIFTED INTO FIRST GEAR (D1).

CORRECTION:

REFLASH THE VCM WITH THE APPROPRIATE PART NUMBER LISTED BELOW.

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.

SERVICE PARTS INFORMATION NEW CALIBRATION VERSION FILE NUMBER ----------------------------------------- 16216189 CD ROM 1996 DISC 22

THIS NEW CALIBRATION IS AVAILABLE WITH THE CD ROM 1996 DISC 22 UPDATE.

WARRANTY INFORMATION FOR VEHICLES REPAIRED UNDER WARRANTY, USE:

LABOR OPERATION LABOR TIME J6352 OFF-CAR USE PUBLISHED J6355 ON-CAR 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.