PURPOSE: Under very cold operating conditions of - 13 degrees Celsius (9 degrees Fahrenheit) or colder, customers may comment that the automatic transaxle has a sluggish upshift or shifts from 1st to 3rd gear without engaging 2nd gear. (This shift from 1st to 3rd gear may feel like a sluggish shift to the customer.) Customers may also notice that the automatic transaxle does not shift into 4th gear. These conditions are normal when the automatic transaxle oil temperature is - 13 degrees Celsius (9 degrees Fahrenheit) or colder, and exists until the automatic transaxle warms - up to - 12 degrees Celsius (10 degrees Fahrenheit).
Due to a cold weather shift schedule, the powertrain control module (PCM) will shift the automatic transaxle from 1st gear to 3rd gear and not allow a 4th clutch upshift until the automatic transaxle oil temperature sensor senses that oil temperature is -12 degrees Celsius (10 degree Fahrenheit) or warmer.
Also, this cold weather shift schedule will be more noticeable to the customer when outside air temperatures are well below - 13 degrees Celsius (9 degrees Fahrenheit). This is due to the extended time required to warm-up the automatic transaxle oil temperature to - 12 degrees Celsius (10 degrees Fahrenheit) or warmer.
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.