VEHICLES WITH SIR (AIR BAG) ON SNOWPLOW APPLICATIONS. GMC Truck Yukon

REVISION: 01/06/95

THIS BULLETIN IS BEING REVISED TO DELETE THE IMPORTANT STATEMENT AND ENTER IT IN THE FORM OF Q/A. PLEASE DISCARD BULLETIN 46-90-04 (SECTION 9 - ACCESSORIES). ----------------------------------------------------------------------

SUBJECT: INFORMATION ON VEHICLES WITH SIR (AIRBAG) ON SNOWPLOW APPLICATIONS

MODELS: 1995 CHEVROLET AND GMC TRUCK C/K MODELS WITH SIR

SOME FREQUENTLY ASKED QUESTIONS CONCERNING THE EFFECTS OF SNOWPLOW APPLICATIONS ON SIR (AIRBAG) INFLATION.

Q: WHAT IS THE SPEED NECESSARY TO DEPLOY THE AIRBAG? A: THE AIRBAG WILL DEPLOY ABOUT 15 MPH (24 KPH) WHEN THE VEHICLE IMPACTS AN IMMOVABLE WALL; HOWEVER, THIS VELOCITY THRESHOLD DEPENDS ON THE VEHICLE DESIGN AND MAY BE SEVERAL MILES PER HOUR FASTER OR SLOWER. THIS 15 MPH (24 KPH) IMPACT IS APPROXIMATELY THE SAME LEVEL OF IMPACT AS HITTING ANOTHER STATIONARY IDENTICAL VEHICLE HEAD-ON AT ABOUT 30 MPH (48 KPH).

Q: WILL THE AIRBAG DEPLOY WHEN HITTING A MANHOLE/SEWER COVER WITH THE PLOW? A: NO, IT SHOULD NOT DEPLOY UNDER THIS CONDITION IF THE TRIP MECHANISM ON THE SNOWPLOW IS OPERATIONAL.

Q: WILL A SIDE OR REAR IMPACT OR ROLL OVER CAUSE THE AIRBAG TO DEPLOY? A: NO, THE AIRBAG IS DESIGNED TO DEPLOY IN THE EVENT OF A FRONT OR FRONT CORNER IMPACT OF SUFFICIENT SEVERITY.

Q: WHAT TYPE OF TESTING DOES NORTH AMERICAN TRUCK GROUP (NATG) PERFORM TO VALIDATE THE SIR SYSTEM? A: NATG ENGINEERING PERFORMS BARRIER TESTS, SLED TESTS, DURABILITY TESTS, AND FIELD TESTS TO VALIDATE THE SIR SYSTEM. FIELD TESTING INVOLVED A TOTAL OF 11 SNOWPLOW FLEETS IN VARIOUS REGIONS ACROSS THE U.S. AND CANADA.

Q: DOES THE SNOWPLOW "ROLL OVER" OR TRIPPING MECHANISM FEATURE ELIMINATE AIRBAG DEPLOYMENT? A: THE TRIPPING MECHANISM SHOULD BE OPERATIONAL WHEN PLOWING SNOW TO ENSURE PROPER SIR OPERATION. AIRBAG DEPLOYMENT IS DETERMINED BY THE DECELERATION LEVEL OF THE VEHICLE. MANY FACTORS SUCH AS THE TRIPPING MECHANISM AND THE TYPE OF SNOWPLOW MOUNTING SYSTEM INSTALLED ON THE VEHICLE CONTRIBUTE TO THIS DECELERATION UNDER IMPACT CONDITIONS.

Q: DOES GM RECOMMEND ANY PARTICULAR SNOWPLOW SUPPLIER? A: NO, GM DOES NOT RECOMMEND ONE SNOWPLOW SUPPLIER OVER ANOTHER.

Q: DOES GM RECOMMEND SNOWPLOW INSTALLATION ON CHEVROLET AND GMC TRUCK S/T MODELS? A: NO. GM RECOMMENDS THAT YOU DO NOT INSTALL A SNOWPLOW ON CHEVROLET OR GMC TRUCK S/T MODELS.

Q: HOW DOES THE AIRBAG KNOW WHEN TO DEPLOY? A: THERE ARE DECELERATION SENSORS STRATEGICALLY LOCATED ON THE VEHICLE. WHEN THESE SENSORS DETECT THAT THE VEHICLE IS SUDDENLY STOPPING AS A RESULT OF A CRASH OF SUFFICIENT SEVERITY, THEY COMPLETE AN ELECTRICAL CIRCUIT WHICH INITIATES BAG DEPLOYMENT.

Q: IS IT STILL NECESSARY TO WEAR A SAFETY BELT WITH THE SIR SYSTEM? A: YES!! THE AIRBAG SUPPLEMENTS THE PROTECTION PROVIDED BY THE SAFETY BELTS. REMEMBER, AS MENTIONED BEFORE, THE AIRBAG IS DESIGNED TO INFLATE IN MODERATE TO SEVERE FRONTAL AND NEAR FRONTAL CRASHES. SAFETY BELTS CAN PROVIDE PROTECTION IN IMPACTS OTHER THAN FRONTAL AND NEAR FRONTAL.

FIGURES: 0

CAPTIONS: 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.