My car is not shifting right and going up a hill causes the car to run at 35 MPH tops with the RPM gauge over 2000. According to the book a bad transaxle sensor could cause this problem, but a mechanic said the check engine light would come on if the sensor is bad. Is that correct?
[b]The problem might be that the torque converter clutch is failing to disengage.
The TCC couples the up torque converter to provide better fuel economy. The TCC is controlled via a solenoid inside the transmission. When coming to a hill, and the acellerator is pressed, the ECU cuts power to the TCC solenoid. This should disengage the TCC. If the TCC fails to disengage, this would be like climbing a hill with a manual transmission in fifth gear. The vehicle slows down and the engine lugs.
GM vehicles have a history of problems with the TCC solenoid sticking thereby not allowing the TCC to disengage.
What you can do is ask your mechanic to unplug the electrical connector for TCC on the side of the transaxle, and drive the vehicle. If the problem disappears after doing this, you know it’s a problem with the TCC.
One thing to try for this problem is, add a half a can of SeaFoam TransTune to the transmission fluid. The SeaFoam will sometimes clean a sticky TCC solenoid of the gum and varnish that causes it to stick. If this doesn’t work, then the side pan of the transaxle needs to be removed to replace the defective TCC solenoid.