4t65 problems

Hello all! I recently purchased a 2001 Aurora 3.5, but the overdrive does not want to engage. In "D" at speeds when it is supposed to engage, I hear a dull whine and thats it. Selecting "3" eliminates the whine but no overdrive (of course). The fluid is at the correct level and does not smell burnt. The tranny shifts perfectly - its responsive and smooth. Im thinking torque converter is not locking up and might need replacement. Any ideas?

The TC doesn't give you a 4th gear. You may have a bad shift solenoid.

Perhaps - it does not seem that the tranny even attempts to shift

A good test for overdrive is put the car in 3rd gear. Get up to highway speed (50-60mph), turn on cruise control, and then push the shifter into D. If the car does not change gears (like my car) then the Overdrive is not moving from 3rd to 4th gear.

This site does a good job explaining the Transmission converter clutch.

http://tech.oldsgmail.com/trans_TCC.html

It looks like Overdrive is controlled by the solenoid that gets a signal from the ECM to make the gear shift from 3rd to 4th. There are 2 wires that go to the solenoid- 1 for the 3rd gear and the other for 4th.