: TCC converter stuck off

01-10-09, 11:48 AM
Hey everyone. I'm brand new to the forum, but have done some reading on previous posts regarding this issue. I have a '98 STS, and I'm not asking for you all to be redundant (because I know it's annoying haha.) My question is just to see if those of you who've had this issue and kept driving the car.....what were your results? If it was a true TCC issue, did you find it more beneficial to essentially burn up the trans and get a new one later, or would you have gone back and spent the $2500-3000 to fix it in the beginning? Thank you in advance!

01-10-09, 12:56 PM
The TCC problem boils down to: Drive It or Live With It.

If the car is primarily used for city and near suburban driving, TCC is really not necessary, as it operates to remove the last bit of slip between the transmission stator and rotor, essentially providing 5th "gear". You may never miss the extra 300 or so RPM decrease it provides.

If the car is a highway runner, the decreased engine speed gives slightly better gas mileage and longer engine life.

The general consensus is that the transmission will not "burn up", just work harder under highway conditions.

To fix it or not is entirely up to you and your car requirements. The condition MAY eventually begin to set malfunction codes and lights, which MIGHT affect emissions testing.......of course, there's always the possibility of something else going wrong, transmission-wise.

01-10-09, 04:45 PM
Thank you, submariner. My STS is the only car I own, which makes it a daily driver. I've had a couple shops tell me it is, in fact, this particular issue via them confirming the cause of the Service Engine light. I'm just now beginning to research and understand what it's all about. The car seems to be running just fine. I took it out this afternoon and it's still shifting into Overdrive. At any rate, thank you for the quick response!

01-10-09, 07:14 PM
????? If TCC is operating, when on a smooth level road, accelerate with an even, moderate pedal. The transmission should go through 4 distinct shifts, and, as speed and load level off above 41 mph or so, TCC should gently kick in and reduce RPM about 300 revs. Now, drive a half mile. On a level road, light load, hold your gas pedal foot steady and touch the brake pedal with your left foot. 300RPM increase ??? TCC is working.

01-11-09, 11:21 AM
Just got back from testing your instructions. There's not a lot of level roads around here, but I did the best I could. I think I only counted 3 shifts on the moderate acceleration test, plus the overdrive shift. The car is running 2000 rpms at 60mph, which is what it has always done since I've owned it. I tested the second part of what you said by touching the brake pedal at cruise, and I'd say I noticed the small rpm increase about 75% of the time (I tested it several times.) Will that slight increase occur at faster cruising speeds, i.e. 55-60mph? I noticed it would have the increase more often around 45mph, but not as often when testing it from around 60mph. Is it possible the TCC would work intermittently if this issue were indeed present, or should it either work 100% or 0% of the time? And I realized my first post wasn't very clear. The car has the SES light on for the TCC code, but I haven't noticed any driveable differences in the car.

01-11-09, 12:03 PM
And secondly, it's throwing a multitude of other codes. Don't quote me right now, but I believe there were a couple O2 sensor codes and maybe one or two others. I'll go to a shop tomorrow after work and write down every single code.

01-11-09, 12:42 PM
Touching the brake should disengage the TCC at any speed and you should see a small RPM decrease. It is possible that it is intermittent.

The best way I have found to feel the TCC lockup is to cruise at 40 MPH and then ever so slightly ease it up to 41. The lighter the acelleration, the easier it is to feel it.

01-11-09, 12:53 PM
2000 RPM at 60 is good for an STS (3.71:1 final drive) with an operating TCC. 2300 or so at 70. (My bad: 3 shifts (4 gears) and the fourth "shift" is TCC engaging.) Under light to moderate loads TCC should function above 41-42 mph all the time, and never when you're doing WOT and high speed maneuvering.

You don't need a shop to pull all your codes. Read the stickys at the top of this forum, Northstar Performance, and Cadillac Technical Tips. Pour a decent Scotch&water and experiment with code work, noting whether each is History or Current. Know that codes will go to History after 4 successful start-run cycles, and will auto-clear from memory after 40 such cycles. When you get familiar with the code pushbutton drill, a nice twist is when the DIC asks "All codes" press the NO function. The first module will display as XXX ?. Press YES. Now you can toggle through each module at leisure, using the UP/DOWN toggle to go forwards or backwards and YES/NO to view codes and reset as you please. Otherwise, the modules sequence automatically and you'll lose track of the codes and miss a few. You won't hurt a thing......practice. If you get to the end and clear all codes the car will not pass an OBD-II plug-in emissions for about two weeks. The manual module stepping operation described allows you to delete only the codes you want gone.

01-11-09, 03:05 PM
Again, thank you submariner and Ranger.

Ok, I went and fiddled around with the car and checked the codes. (Thank you for showing me how to get them:).) I have 8 codes and they all came up as History....

U1255-Class 2 Communication Malfunction (Serial Data Line Malfunction)
U1301-Class 2 Short to Battery
U1128-Loss of Communications with IRC
U1064-Loss of Communications with DIM
B1983-Device Power Circuit Low
P0603-Control Module Long Term Memory Reset
P0741-TCC System Stuck Off
P1611-Loss of CVRTD Serial Data

Does the plot thicken?

01-11-09, 03:15 PM
The only code of interest is the 0741.........Clear the whole mess and drive for a couple of weeks.......don't get paranoid over codes, especially voltage and data hiccups. You might check toward the end of the week, jot down any codes but don't clear them: create your own history. If (when ?) the SES light comes on, you could check what code set it and go from there......

01-11-09, 03:28 PM
Ok, will do. I'll keep my fingers crossed!

01-12-09, 07:36 PM
Cleared the codes this morning and the SES light came back on this afternoon. Checked it, and sure enough, P0741. A shop said they'd be able to tell whether it's a solenoid or the tcc, which would take them an hour to diagnose. Said they'd charge me $75. I'll probably have that done to at least know where I stand. Any other suggestions for round two? If so, I'm all ears.

01-15-09, 12:17 PM
My original trans had that problem - I drove it for many miles with no additional problem. I do live in the desert where the temps are over 100 for several months, so I added an external trans fluid cooler to help take up some of the extra heat caused by TC slippage. I decided that it did not pay to repair the TCC problem - better to replace the trans if it failed...which it never did.

When I replaced rather than repaired the engine with a used engine, I also replaced the trans with a used trans at the same time, and that trans has worked just fine for 27K miles, so far. The used engine's HGs did fail just like the original engine's did after 23K miles, and I did the whole thread deal repair at that time - I would have done that the first time if I had known the info I have learned here.