Bad ECM or Tranny, can you help?

[Frustoyotated]

2005 Corolla CE Auto, 65k miles. C.E.L. on dash, error code P0741. Torque Converter Clutch Solenoid is supposedly out.

Curiously, the car shifts fine. Runs smooth. Absolutely no symptoms of transmission problems. The ECM is 89661-02C12, so it does not fall under the Toyota Service Bulletin (00804, I think) that outlines procedures for diagnosing and replacing the ECM. Toyota says the transmission needs to be replaced ($4,000) and refuses to even entertain the notion that it might just be a faulty ECM.

I'm considering having an independent mechanic replace the ECM.

Any suggestions?

[mikered30]

Could it be a speed sensor issue besides the torque converter, like a solenoid or clutch? I dont think swapping out the ECU will help, a new ECU is quite expensive and could become more costly if it does not solve the problem. Can you take it to a different dealer and tell them about the TSB that applies to the code and see what they say?

[Slaander]

Originally Posted by Frustoyotated

2005 Corolla CE Auto, 65k miles. C.E.L. on dash, error code P0741. Torque Converter Clutch Solenoid is supposedly out.

Curiously, the car shifts fine. Runs smooth. Absolutely no symptoms of transmission problems. The ECM is 89661-02C12, so it does not fall under the Toyota Service Bulletin (00804, I think) that outlines procedures for diagnosing and replacing the ECM. Toyota says the transmission needs to be replaced ($4,000) and refuses to even entertain the notion that it might just be a faulty ECM.

I'm considering having an independent mechanic replace the ECM.

Any suggestions?

the solenoid inside the transmission has so many pressure holes, once transmission oil mixed with water, it will turn to something like jello in white color and will stucks on those pressure hole, even they replace the solenoid is not 100% sure will fix the problem since all those jello stuff would be already stay on those discs. that is the reason they they told you need to change the whole transmission. that is easy fix for the dealer. does they said it under warranty? there should be power train warranty which is 160k Km in canada, but I don't know what is the numbers in states.

here is the a cut open auto transmission picture

[Frustoyotated]

The main issue is that Toyota (two dealers, and the Customer Experience hotline) have said that the only solution is to replace the transmission. This is fine on their dime, but the driveline is out of warranty (by about 4,800 miles, 8% of the warrantied mileage), so it is my dime we're talking about.

Based on the Toyota service bulletins for ECMs from this generation, I feel they should consider the possibility that it might be an issue with the ECM, rather than the transmission. However, they recite from their book of numbers that the serial number of my ECM is not one of the known problem ones. It's a chicken and the egg problem. How did the known problem ECMs get discovered?

Since it is my money we're talking about, I think I should be allowed to explore alternate solutions to the problem, based on the evidence of the actual car, not the serial numbers listed in a book. Toyota refuses to consider this.

Further research has led me to understand that a transmission with the solenoid problem could appear to function OK for a while. So, we're monitoring gas mileage on the car, and when we do the next oil change we'll look at the transmission fluid again to see if it shows any signs of being burnt.

[Frustoyotated]

Originally Posted by mikered30

a new ECU is quite expensive and could become more costly if it does not solve the problem.

One dealer said they had to replace the transmission and the ECU. When I asked the Customer Experience representative why that couldn't be done as a two-step process (replace ECU first, see if that solves problem) he insisted that the transmission had failed, so it would have to be replaced.