NO UPSHIFT/INTERMITTENT DTC 81 AND 82 OR P0753 AND P0758. GMC Truck Safari

REVISED: 05/15/95

THIS BULLETIN IS BEING REVISED TO CORRECT THE TITLE/SUBJECT AND MODIFY THE SECOND PARAGRAPH. ----------------------------------------------------------------------

REVISION: 07/24/96

THIS BULLETIN IS BEING REVISED TO INCLUDE THE 1996 MODELS, TO ADD S/T AND M/L TO SERIES AND TO ADD FUSE #24 ON S/T MODELS. PLEASE DISCARD CORPORATE BULLETIN 57-65-08 (SECTION 6E - ENGINE FUEL & EMISSION). ----------------------------------------------------------------------

SUBJECT: INFORMATION ON NO UPSHIFT/INTERMITTENT DTC 81 AND 82 OR P0753 AND P0758

MODELS: 1995-96 CHEVROLET AND GMC C/K, S/T, M/L MODELS WITH A HYDRA-MATIC 4L60-E (M30) OR A 4L80-E (MT1) AUTOMATIC TRANSMISSION

SOME OWNERS MAY COMMENT ABOUT NO TRANSMISSION UPSHIFT. IN CONJUNCTION, DIAGNOSTIC TROUBLE CODES (DTC) 81 AND 82 FOR 1995 MODELS OR P0753 AND P0758 FOR 1996 MODELS ARE SETTING INTERMITTENTLY AND THE NORMAL DIAGNOSTIC PROCEDURES ARE NOT LEADING TO A RESOLUTION OR THE CONDITION CANNOT BE DUPLICATED.

IMPROPER USE/INSTALLATION OF AFTERMARKET ELECTRONIC ACCESSORIES, SUCH AS A REMOTE START SYSTEM, AN ALARM, A RADAR DETECTOR, A RADIO, OR ANY OTHER TYPE OF ELECTRICAL ACCESSORY, MAY CAUSE DTC 81 AND 82 OR P0753 AND P0758 (SOLENOID ELECTRICAL FAULT) TO SET WHEN THE ACCESSORY IS USED. DTC'S 66 AND 67 OR P1860, P1864 AND P1886 CAN ALSO SET ON 4L60-E. WHEN DTC 81, 82 OR P0758 SET ON 4L60-E THE TRANSMISSION DEFAULTS TO 3RD GEAR ONLY. WHEN DTC P1860, P1864 OR P1886 SET ON A 4L60-E, THE TCC WILL BE INHIBITED. WHEN DTC 81, 82 OR P0758 IS SET ON A 4L80-E, THE TRANSMISSION WILL DEFAULT TO SECOND GEAR ONLY. BOTH TRANSMISSIONS WILL RESUME NORMAL OPERATION WHEN THE DTC'S ARE CLEARED OR WHEN THE IGNITION KEY IS CYCLED OFF LONG ENOUGH TO ALLOW THE DTC TO BECOME A HISTORY CODE.

WHEN SERVICING A 1995 OR 1996 VEHICLE EQUIPPED WITH A HYDRA-MATIC 4L60-E (M30) OR A 4L80-E (MT1) AUTOMATIC TRANSMISSION FOR DTC 81 AND 82 OR P0753 AND P0758, (DTC'S 66 AND 67 OR P1860, P1864 AND P1886 MAY ALSO SET ON A 4L60-E), LOOK FOR THE INSTALLATION OF A REMOTE START DEVICE OR OTHER AFTERMARKET ELECTRONIC ACCESSORIES. OPERATE THE REMOTE START DEVICE OR OTHER AFTERMARKET ELECTRONIC ACCESSORY(S) TO SEE IF DTC 81 AND 82 OR P0753 AND P0758 WILL SET. IF THE CODES SET WHEN THE DEVICE IS USED, THE DEALERSHIP WILL NEED TO REFER THE CUSTOMER TO THE COMPANY THAT INSTALLED THE ACCESSORY(S) FOR CORRECTIONS WITH ONE EXCEPTION.

IF THE CODES ARE SETTING WHEN A REMOTE START SYSTEM IS BEING USED, CHECK TO SEE THAT FUSE #20 (FUSE #24 ON S/T), TRANS FUSE, IS BEING SUPPLIED BATTERY VOLTAGE DURING THE REMOTE START SYSTEM OPERATION. IF THE REMOTE START SYSTEM IS NOT SUPPLYING VOLTAGE TO FUSE #20, THIS WILL CAUSE DTC 81 AND 82 OR P0753 AND P0758 TO SET BECAUSE OF NO VOLTAGE TO THE SHIFT SOLENOIDS. CONTACT THE INSTALLER OF THE REMOTE START SYSTEM TO DETERMINE THE PROPER WIRING TO SUPPLY BATTERY VOLTAGE TO FUSE #20.

IF THE VEHICLE DOES NOT HAVE ANY AFTERMARKET ELECTRICAL EQUIPMENT INSTALLED AND THE DTC'S ARE SETTING INTERMITTENTLY, INSPECT CIRCUIT #1020, TRANSMISSION BATTERY FEED, FOR PROPER VOLTAGE.

PLEASE BE AWARE THAT ADD-ON ELECTRICAL EQUIPMENT SHOULD NOT BE WIRED INTO THE TRANSMISSION POWER CIRCUIT AT ANY POINT. THIS COULD CAUSE ERRATIC ELECTRICAL TRANSMISSION OPERATION AND FALSE CODES TO SET.

REPAIRS TO THE AFTERMARKET SYSTEM ARE NOT A RESPONSIBILITY OF THE NEW VEHICLE WARRANTY.

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.