I have a 97 Eldorado base Cpe. SES light came on my code was P0741.
Which is a general code the TC can be stuck on or off my was stuck off. It is my understanding with the stuck on TC comes a lot of driveability problems such as stalling, bucking etc. My car drove buttery smooth. The only thing the mileage did start to go down from 19 city to about 16. I was informed by a tranmission specialist the reason I hadn't noticed any promblems was I still had all four gears including overdrive, the TC was just not locking up.
I have read many of these threads and most state it the the solenoid. Since my car was shifting fine I had a reall problem paying $900.00 to pull the tranny to replace a $70.00 switch. By the way solenoid looked fine. GM has a service bulletin to fix the problem which recommends dropping the tranny inspecting, checking the seals, and replacing the torque convertor etc solenoid. I was told a service writer at a dealship people drive these things for years I drove my for 6000 miles, the previous owner probably had done same thing, since the light came on in about the first 200 miles on the highway home.
I got bold and wrote a Advanced Transmission who repaired mine, they offered a free road test, and diagnostic test. They dropped the pan checked the fuild found some metal in the bottom of the pan. Computes show torque convertor was not locking up. They gave me a qoute of $1224. without the torque convertor. I told him GM recommend replacing the TC. After about two weeks I decided to have the work done. The oriiginal estimate was to replace the solenoid conv cl, imput sensor, vale cover and gaskets. Advance talked with a guy who rebuilds Torque Converter he also recommended he replace the torque convertor. He stated if convertor had was operated low on fulid it should was a probably torched. New estimate $1698.12 the torque convertor is $325. I think if paying $900.00 in labor you should take care everything that is questionable. He had the car two and half days a part was late. After they test drove the car about 40 miles, and ran a computer check which indicated the torque convertor was locking up. The Service Engine Light also went out, and has stayed out.
The car runs like a new car, it more powerful, and with their test driving, and stop and go traffic, the car was getting 20.2 miles per gallon in town up about 4mpg.
They find a bad seal on gasket on the rear input sensor. The car only has 71000 miles all this was probably caused by the previously owner putting in to small of a battery, and it was also at about 50% capacity. The tranmission is Electronic. I changed the Battery before I had the repairs done, and car ran better, I also had put a new alternator in it, probably related to the battery too, the Dealer did the alternator, and did not check the old battery Wal Mart , told me my battery was bad on a oil change! Wow! If my car was a junker or high mileage I would have probably drove it until it quit. At one time someone paid about $45,000. for this car I figured it is worth a $1700. repair. I am gone drive it to Texas from Colorado next month I will update this! I hope this helps someone!
I took my 02 deville to a Cadillac dealer. They quoted me $1,100 to replace the TCC solenoid. They then called and recommended dropping the side valve body to inspect the sprocket and seal for wear and then replace the TC if wear was present! Well the sprocket and seal were bad and rumor has it that a whole series of the 4T80e trans suffer from this because of the valve body was not machined properly. Well $2760 latter and it is beautiful. I picked up 4 mpg and it feels stronger as well. I wish I could have found a tranny shop that could have done it for less. So minor regrets.