2000s 2000 Eldorado ETC P0741 Code

[Mike Shawgo]

Hi everyone, Mike again.

I just had my mechanic do a transmission fluid and filter change, and new pan gasket on my 2000 Eldo ETC. The next day I got a Service Engine Soon light. Checked the codes and it had a P0741, TCC System Stuck OFF. This seems to me to be related to the fluid change, as I had no issues previously. Any idea what the issue might be?  Also, I've seen various internet posts ranging from "Ignore the problem and continue to drive" to "don't drive the car, you will ruin your transmission."

Mike
#20545

[Dave Shepherd]

Complex diagnosis. Check this link. https://www.kbb.com/obd-ii/p0741/

[TJ Hopland]

Historically speaking (back in the 1900's) not having the torque converter lockup was only going to cost you some gas but I don't know what they were using in 2000 4T85e? 

I'm sure its all electronic so not like the 80's where the was just one wire and one solenoid.  Its got a pretty large multi pin connector and a whole bank of control solenoids usually located in the pan but again I don't know that model.  The ones I have been in its not like the internal wires and connectors are big things that could easily be knocked off they tend to be kinda a pain to get off but I suppose this is old enough that maybe the plastic connectors or locks have become brittle and got bumped during the service?  Maybe see if you can find a diagram and see if that one is near the filter?

I guess the other question would be what other TCC related codes are there?  On something like this there would likely be other codes like circuit high or low indicating it being disconnected or shorted so maybe the issue has nothing to do with the actual TCC solenoid?  Can you find more info on that code like the conditions to set it?  And if it mentions related codes?  Im not sure if this also has a pending code section? 

[smokuspollutus]

This usually means the sensor needs to be replaced. Unfortunately the trans has to be rebuilt to do that. If you do not have emissions in your state, best to leave it alone.

[TJ Hopland]

I would want to see a Cadillac specific diagnostic chart for this issue.  Too many people end up going down the wrong path using the generic definitions. 

[Mike Shawgo]

Smokus, are you talking about the TCC sensor? I don't think that is so difficult to replace. Of course I'm not doing this work, a mechanic will do it. Right now they want to clear code, have me drive it a bit and see if it comes back.

[smokuspollutus]

I should say, it really it isn't so much the sensor as it is the converter circuit. As the transmission ages small internal leaks start to happen. Changing old fluid out for fresh can have the effect of cleaning a bit of gook that was marginally sealing something, which is probably what happened here. So there's probably something internally leaking on the converter apply circuit that prevents it from locking up as designed.

When the torque converter is not locking to the satisfaction of the desired vs observed RPM drop, it sets a code. This is classed as an "emissions" issue because the engine isn't operating as efficiently as it should be, so the check engine light illuminates.

Short of rebuilding the transmission the leak probably isn't going to be found. Provided you don't have emissions testing, the best thing you can do is drive it and take a small mpg penalty. If you do have to contend with emissions, you may have to get creative.

I've wanted one of these for a while, but in my state, a car of this age still has to pass emissions testing. Ironically of the ones that I looked at that didn't have either head gasket or oil leaks, the rest set this code when driven on the highway. Fortunately a friend who had been burned by this issue advised me beforehand and I was able to avoid them.

Good news is the car will probably run forever even with the issue.
 

[Mike Shawgo]

Hi everyone,

Well, not so lucky with this one. I cleared the code hoping it wouldn't come back, but it did. Took it to a trans shop, and you guys were right--needs a transmission rebuild. I guess I'll go ahead with it. The trans shop said they could try various things like replacing the torque converter, TCC solenoid, etc, but if that didn't fix it, I would just be wasting money. And, I DO have to have an emissions test for this car in the state of Illinois.

Thanks for your comments,

Mike