I have a 2002 Eldorado etc, 70500 miles. with a TCC service code. Overdrive was engaging (I drove 50mph, tapped the brake, the rpms would jump about 250.) I put and other 100 miles on her and when I did the same test no increase in rpms. I’ve been told I had to have the transmission rebuilt ($4,000) to do nothing. I like the last one. Road mileage has dropped from 25 to 27 down to 23 to 24.I guess overdrive is not engaging now.
This code and set of symptoms usually means the torque converter clutch solenoid has failed and is no longer locking the torque converter at cruising speed. The solenoid is accessed through the side cover of the transmission, which unfortunately cannot be removed with the transmission in the car. The transmission doesn’t have to be rebuilt to correct this problem, but it does have to be removed from the vehicle. I quoted this job to a customer once years ago. I can’t remember how much the estimate was, but it was enough that the customer decided to live with the problem.