ENHANCED INSPECTION MAINTENANCE PROGRAMS. Chevrolet Chevy MD S Chassis 1993

THIS BULLETIN IS BEING REVISED TO INFORM "GM OF CANADA" AND "NAES" DEALERS THAT THEY ARE NOT AUTHORIZED TO UTILIZE THIS SERVICE BULLETIN

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"GM OF CANADA" AND "NAES" DEALERS ARE NOT AUTHORIZED TO UTILIZE THIS SERVICE BULLETIN.

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SUBJECT: INFORMATION ON ENHANCED EMISSION INSPECTION MAINTENANCE PROGRAMS - EQUIPMENT REQUIREMENTS

MODELS: 1994 AND PRIOR PASSENGER CARS AND TRUCKS

THE INTENT OF THIS BULLETIN IS TWOFOLD; FIRST TO INFORM YOU OF THE UPCOMING ENHANCED INSPECTION MAINTENANCE (I/M) PROGRAM WHICH WILL BE IMPLEMENTED IN SPECIFIC REGIONS OF THE COUNTRY BEGINNING IN JANUARY 1995 (JULY 1994 IN MAINE), AND SECONDLY TO **ADVISE AGAINST THE PURCHASE OF EMISSION RELATED EQUIPMENT AT THIS TIME.**

THIS "ENHANCED" I/M TEST (ALSO REFERRED TO AS THE IM240 TEST) ACTUALLY CONSISTS OF THREE SPECIFIC TESTS (AND ANY ADDITIONAL TESTS INDIVIDUAL STATES MAY REQUIRE). THEY ARE:

**1.) THE IM240 TEST-** THIS TEST CONSISTS OF A TRANSIENT DYNAMOMETER TEST EVENT WHICH WILL BE CONDUCTED AT CENTRALIZED (STATE OWNED) TEST FACILITIES. THE EXHAUST GASSES MEASURED DURING THE IM240 TEST EVENT ARE: HC, CO, AND NOX. THIS TEST EVENT IS MUCH MORE COMPREHENSIVE THAN CURRENT I/M TESTS.

**2.) THE PURGE FLOW TEST-** THIS TEST MEASURES THE FLOW OF UNBURNED HYDROCARBONS THROUGH THE PURGE SOLENOID DURING THE IM240 TEST. THE OBJECTIVE IS TO DETERMINE THAT SUFFICIENT FLOW IS PRESENT UNDER THE PROPER CONDITIONS.

**3.) THE EVAPORATIVE SYSTEM PRESSURE TEST-** THE OBJECTIVE OF THIS TEST IS TO EVALUATE THE INTEGRITY OF THE FUEL TANK VAPOR RECOVERY SYSTEM. IT IS CONDUCTED BY PRESSURIZING THE FUEL TANK AND FUEL VAPOR LINES. PRESSURE IS THEN MONITORED TO ASSURE THE SYSTEM IS LEAK-FREE.

CURRENTLY, THERE ARE APPROXIMATELY 30 STATES WHICH WILL IMPLEMENT THE ENHANCED I/M PROGRAM. IN MOST CASES, THE TEST PROGRAM WILL BE LIMITED TO MAJOR-URBAN AREAS, ALTHOUGH SOME STATES HAVE ELECTED TO IMPLEMENT A STATEWIDE PROGRAM. CHECK WITH YOUR LOCAL ENVIRONMENTAL AGENCY TO DETERMINE IF YOU WILL BE AFFECTED BY THE ENHANCED I/M PROGRAM.

CORRECTION OF VEHICLE FAILURES IDENTIFIED BY THE ENHANCED I/M PROGRAM WILL REQUIRE SPECIALIZED EQUIPMENT AND DIAGNOSTIC TECHNIQUES. GENERAL MOTORS SERVICE TECHNOLOGY GROUP IS DEVELOPING AND VALIDATING PROCEDURES TO DIAGNOSE AND REPAIR VEHICLES WHICH FAIL THE NEW REQUIREMENTS. OUR OBJECTIVE IS TO PROVIDE EFFECTIVE REPAIR TECHNIQUES UTILIZING PROVEN EQUIPMENT AND TO ENSURE OPTIMAL VALUE AT THE LOWEST POSSIBLE COST. **PLEASE REFRAIN FROM PURCHASING ANY EMISSION RELATED EQUIPMENT (I.E. EXHAUST GAS ANALYZER, DYNAMOMETER) UNTIL NOTIFIED BY GENERAL MOTORS SERVICE TECHNOLOGY GROUP TO AVOID UNNECESSARY EXPENSE.** MANY PRODUCTS CURRENTLY BEING MARKETED ARE EITHER INCAPABLE OF PERFORMING THE REQUIRED DIAGNOSTIC AND REPAIR FUNCTIONS OR INCLUDE EXPENSIVE FEATURES THAT MAY NOT BE REQUIRED. YOU WILL BE NOTIFIED OF OUR FINDINGS AS INFORMATION BECOMES AVAILABLE.

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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.