THIS PRELIMINARY INFORMATION COMMUNICATION PROVIDES INFORMATION TO THE TECHNICIAN ABOUT VEHICLES THAT HAVE A VIBRATION THAT IS FELT BETWEEN 1200 – 1400 ENGINE REVOLUTIONS PER MINUTE WHEN IN ACTIVE FUEL MANAGEMENT V4 MODE. TECHNICIAN WILL NEED TO USE CH 51450-NVH PICO OSCILLOSCOPE DIAGNOSTIC KIT TO MEASURE THE FREQUENCY OF THE VIBRATION. TECHNICIAN WILL NEED TO INSTALL AN EXHAUST DAMPER AND EVALUATE THE VEHICLE. IF THE VIBRATION IS NOT REDUCED, THE THREE-WAY CATALYTIC CONVERTER AND CAB MOUNT SETTLING PROCEDURES WILL NEED TO BE COMPLETED. THIS CONSISTS OF LOOSENING THE EXHAUST CLAMPS AND BODY MOUNTS, SETTLING THE COMPONENTS AND TORQUEING THEM BACK TO SPECIFICATION.