For 1990-2009 cars

# INCORRECT VACUUM CONTROL VALVE MAY CAUSE DAMAGE/CONTROLLER

USE OF AN INCORRECT CRUISE CONTROL VACUUM CONTROL VALVE ON A 1982 V-6 OR A 1982-1983 DIESEL EQUIPPED VEHICLE MAY RESULT IN DAMAGE TO THE CRUISE CONTROLLER. THE GMWDD PARTS CATALOG, DATED 1/83, GROUP 3.885, HAS INCORRECTLY TRANSPOSED THE HT4100 VACUUM CONTROL VALVE PART NUMBER WITH THAT FOR DIESEL AND V-6 VEHICLES. THE CORRECT PARTS USAGE IS AS FOLLOWS: APPLICATION 1982-1983 HT4100 PART NUMBER 1997597 CONNECTOR BODY COLOR BLACK DIODE IN VALVE? YES APPLICATION 1982-1983 DIESEL PART NUMBER 1997478 CONNECTOR BODY COLOR WHITE OR BLACK DIODE IN VALVE? NO APPLICATION 1982 V-6 PART NUMBER 1997478 CONNECTOR BODY COLOR WHITE OR BLACK DIODE IN VALVE? NO THE VACUUM CONTROL VALVE USED ON HT4100 EQUIPPED VEHICLES CONTAINS A DIODE TO PREVENT DAMAGE TO THE ECM. SOME V-6 AND DIESEL EQUIPPED VEHICLES MAY BE WIRED SUCH THAT IF A VACUUM CONTROL VALVE CONTAINING A DIODE IS USED, THE DIODE WILL APPEAR AS A SHORT CIRCUIT TO THE CRUISE CONTROLLER.

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.