It is a very common issue with the 3800 engine. The key is the loss of RPM which the Crank sensor controls and when the computer has no RPM information, it turns off the Traction control. The Crank sensor is made up of two parts. One controls the tach signal the other controls ignition. At least the side that allows you to continue to drive went out, Ive had it happen both ways and if the ignition side goes out you'll be pretty much dead in the water.