Hi! Sorry my bad english, i'm writing from Finland

I have 2006 IS250 automatic with 165km mileage and a while ago VSC light popped up. Code said P2757 "Torque Converter Clutch Pressure Control Solenoid Control Circuit Performance or Stuck Off".. So i had my transmission fluid changed and they were pretty bad. Car worked fine couple of weeks after oil change until same code appeared again. So i had SLU solenoid and tranny fluid changed. After ~5km driving from workshop VSC light appeared again and still same code and definition..

So what the heck is the problem? In my opinion car shifts fine, all gears work, no stuttering or slipping gears. Even former Toyota mechanic drove it and said that it shifts fine. Do i need new tranny, Torque Converter or what should i do..

 

Are you sure that you replaced the correct solenoid?

What is your mileage?

Did you replace or clean the pan filter when you dropped it?

Do you notice any gears shifting roughly, especially when the transmission is cold? Did you notice an improvement with shift quality after you replaced the existing solenoid?

The only other thing I can suggest is to drop the pan again and replace ALL of the solenoids.

If aplicable to your vehicle, see if you can perform a transmission reset sequence. Try to reset the code one more time.

 

Mileage is 165,000km.. And now that you asked, i started to think that it could have been wrong solenoid we changed. The solenoid we changed was SLU solenoid but it could be TCC solenoid which is faulting. I haven't notice any problems with shifting. Filter was cleaned when mechanic dropped the oil pan. You might be right that it was wrong solenoid. I have to order TCC solenoid and replace that.. Won't replace all solenoids, at that point it's cheaper replace tranny with used one. But thanks for answering!

 

There is a big misconception about transmission codes. The TCU can detect opens and shorts within the solenoids it controls. If it is not an open or a short than the TCU only knows a command was given but does not know if it was followed.

An example is this: TCU command solenoids to change state for a gear change from 1st to 2nd. It knows it's in first as it knows the turbine input speed and the tail shaft output speed. So when it selects the next gear it looks at these same shafts and compares them to a MAP lookup table and does yes/no. Do the new speeds indicate we are in second gear? If yes, all is good. If no, it points the finger at the last function performed which was a state change for select solenoids.

Here is where assumptions are made and money is wasted. If the solenoid thrown under the bus tests good, the problem lies elsewhere and solenoid replacement is not going to fix it.

Specific to your cause. The ECU and TCU are throwing a code because they have detected the turbine input RPM is not tracking engine RPM when the solenoid responsible says it should be in lockup but the converters clutch is slipping. Which it could do for many reasons and not involve the solenoid.

Make sense? More testing and less parts swapping is the answer.

 

100% agree, but in the case of solenoids, they are wear items meaning inside a higher mileage gearbox, even if the solenoids are working as they should, replacing them can make your trans feel like brand new again. You'd be surprised how much of a difference new ones make on a gearbox which seems like it's on its way out or not shifting very well/smoothly.

As for replacing all of the solenoids, it's not a bad idea to do so especially with higher mileage due to the reason I just stated above. If you plan to keep the car it makes more sense VS. going through the effort of sourcing a new transmission with unknown mileage, and swapping it in only to realize the used transmission with god knows how much mileage could certainly use a solenoid replacement as well.

But I digress. 160K isn't that high, so you don't need to replace every single solenoid but it wouldnt hurt.

Before ordering a new solenoid, be 100% sure you are replacing the correct one.

 

Transmission oil was bad and probably never been changed before this. So i assume that it has done some damage to solenoids. And because there aren't any other symptoms but Check engine- light i assume that whole tranny isn't totaled. I agree that it would be wise to change all solenoids but in case that they cost 300€/pcs. in Finland it costs too much. I'm not keeping this car, only fixing that i can sell it. This particular car has been bit of a disappointment overall.

 

Post #5 Stop! ^^ have you ever actually worked on a transmission? Why are you telling people to replace anything! Why?!!!!

 

Do you want to explain..? or?

 

Hello, I have Lexus IS 250 from 2006 year with automatic transmission and I have codes P2757 and C1201. I changed the solenoid, oil and filter for the transmission.

Are these codes connected with the ecm and tcm, should I buy knew computer or the problem is with transmission? Has anyone solved this problem?

 

Read this here first. It's not always going to be what the scan tool reads.

Some trouble shoot is required while diagnosing for car DTC codes. In your case it's transmission related.

https://www.sonnax.com/tech_resource...-transmissions

 

Lexus technician here with advice. I didn't see anywhere where you did a transmission reset and a subsequent transmission learn. I would start there instead of changing out solenoids. Find someone or a technician like me who has access to techstream because the reset of the transmission learned values can only be done through texturing not even removing the battery or anything like that

Just another reason to not drain your tranny fluid. Guys it will be fine.