WHEN DIAGNOSING A VEHICLE FOR CUSTOMER CONCERNS SUCH AS NOISE AND/OR VIBRATIONS, IT IS OFTEN NECESSARY TO RUN THE VEHICLE WHILE IT IS SUPPORTED IN THE AIR BY HOISTS OR JACK STANDS. ON LIGHT DUTY TRUCK MODELS WITH FOUR WHEEL DRIVE (4WD) OR ALL WHEEL DRIVE (AWD) THE FRONT SUSPENSION SHOULD NOT BE ALLOWED TO HANG FREE WHILE PERFORMING ON-HOIST TESTING. IF THE FRONT SUSPENSION IS ALLOWED TO HANG FREE, THE CV JOINT WILL BE AT A VERY HIGH ANGLE. THIS WILL LIKELY RESULT IN DAMAGE TO THE FRONT WHEEL DRIVESHAFT BOOTS. IN ADDITION, EXTRA VIBRATIONS MAY OCCUR AND MAY DAMAGE THE FRONT WHEEL DRIVESHAFT JOINTS.
WHEN ON-HOIST TESTING AN AWD OR 4WD LIGHT DUTY TRUCK, SUPPORT THE OUTER END OF THE LOWER CONTROL ARM USING JACK STANDS. THIS WILL REDUCE THE CV JOINT ANGLE AND PREVENT DAMAGE TO THE FRONT WHEEL DRIVESHAFT ASSEMBLY.
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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.
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