For 1990-2009 cars

# TCC ENGAGES AT WRONG SPEED GREASE/DIRT ON SPEEDO HEAD

IF A CONDITION IS ENCOUNTERED WHERE THE TORQUE CONVERTER CLUTCH IS ENGAGING AT THE INCORRECT SPEED, BE SURE TO CHECK SPEEDOMETER HEAD MAGNET FIELD PLATE FOR FOREIGN MATERIAL I.E.: GREASE DIRT ETC. FOREIGN MATERIAL ON THE DRUM COULD CHANGE THE SIGNAL TO THE ECM RESULTING IN ERRATIC TCC OPERATION...

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.