2007 Toyota Corolla with P0741

Joined
Jul 29, 2013
Messages
2,043
Location
Laramie, WY
The Transmission (A245E) Notes: it shifts perfectly, and I mean flawlessly, not a single harsh shift, before and after fluid changes.

My previous experience with this transmission:
I have worked on 15+ A245E transmissions found in the 1998-2008 Corollas and 1998-2002 Chevy Prizms. Most of those cars were from the Midwest region of Missouri & Illinois.

On the A245E transmissions, I have previously done simple D & R with pan drops as well as complete fluid changes using the transmission cooler return line with pan drops, some of these transmissions had 290k, 385k, and 410k on original fluid which was dark brown but never smelled "burnt". I have used Valvoline Maxlife ATF, Valvoline Import ATF, Supertech High Mileage ATF, and Dex II/III ATF from Sam's Club (this ATF was used the most), I have never experienced any issues of any sort.

Background Story:
Originally a Las Vegas car (experienced very HOT temperatures 90% of its life)

I bought the car with 168k miles from south of Oregon, and immediately did an oil change and drove it 2k miles to Chicago.

On my 2k drive back to Chicago, at around ~675 miles (after Salt Lake City UT on I-80), there were miles and miles of steep uphill drive. When the car was in the 3rd gear to maintain power, I got a P0741 CEL for the first time, after doing some light reading, I reset the code and continued on my drive (I got comfortable after reading multiple posts on ToyotaNation and an experienced Toyota tech mentioned that 9/10 time it is dirty fluid) for the remaining ~1325 miles the CEL never came back and the torque converter was engaging as I am aware of the cruising RPMs for this powertrain as I have owned more than 10+ vehicles with this transmission.

The car was driven an additional 3k miles in Chicago before I installed a fully rebuilt engine, along with a complete Transmission Fluid change with a new filter using the radiator return line method.

New Fluid used: Fram ATF Dex III/Mercon + Red Lubegard properly filled to the correct level (Full mark when the transmission is at operating temperature).
Note: I have used the Dex III + red Lugebard combination in 5+ Corollas with the same transmission, and 10+ Celica GTs, never had an issue and yes most of these transmissions had 200k+ miles before the first fluid change, though none of the vehicles ever had a P0741 code (I had never seen that code before even though I have rebuilt 115 of the 1zzfe engines maybe because St. Louis and Chicago being slightly colder climates, the transmission fluid isn't getting as abused? Maybe)

After the fluid change: The P0741 CEL became a permanent code, on the highway, I would reset the code and it would come right back within a couple of minutes no matter how many times I would reset it, the P0741 code came right back, and the torque converter was NOT engaging at all. I drove it 2k miles back to South Oregon to get some paint work done (where I originally bought the car).

I did some more research into it and decided to go to the junkyard and take off some torque converter lockup solenoids from compatible Toyota transmissions.

Junkyard TC Lock up solenoid
1) The 2004 Toyota Corolla AT TC lockup solenoid was made by Denso (grey colored instead of the green one in my car), it passed the resistance test and in the test to get it to actuate, it faintly actuated, therefore I decided not to use it in my car, even though I could be good as I am not completely sure.

2) The 2006 Toyota Matrix AT TC lockup solenoid was made by ASIN (Green colored same as my car), it passed the resistance test, and in the test to get it to actuate, it strongly actuated 4 times in a row but I stopped the test and deemed it a good sensor and decided to install this in my vehicle, I gently cleaned it with brake parts cleaner but not thoroughly.

Additional Background Story:
When I went to pick up my car from the paint job, before driving, I dropped the pan, removed my TC lockup solenoid and replaced it with the one from the 06 Matrix, and put everything back together and, this time I used 4 quarts of Idemitsu Type TLS (Toyota Type IV) ATF as I had some from $2 per quart clearance from AutoZone, this overfilled my transmission by 0.2-0.3 quart which I can drain out if necessary.

After the TC Lockup Solenoid change the vehicle has been driven ~5800 miles 95% highway, the P0741 CEL would only come on acceleration to highway speeds and once I reset the CEL while at highway speeds, the CEL will stay off, and again the torque converter was NOT engaging at all. I am still getting decent gas mileage but I would like to fix this CEL as I don't want any additional wear on my transmission or even the engine as it now cruises at ~200-300 more RPMs at highway speeds than normal, and the mpg have reduced by 2-3 mpg.

I am mechanically inclined but fixing things the first time takes me a while as I don't want to make a mistake and break anything.

Possible options:
1) I can change the fluid again and strictly use Idemitsu Type TLS (Toyota Type IV) ATF but I don't think it is going to do much as the current transmission fluid has Cherry Red ATF fluid now.

2) Drop the transmission pan, remove the valve body take it apart clean everything, lubricate it with fresh ATF, and re-install it, I would like some tips regarding this as watching many videos on YouTube and Google hasn't helped as they are not transmission specific, and I am worried about re-assembly as the repair manual directions I have found online literally states to put it back together and torque it, there isn't any tip or hints of any sort.

3) I could simply get a low-miles used 2008 transmission with 90-105k miles for $200-300 and swap out the transmission and possibly solve my issues as I would intend to buy them from nearby Wyoming as the climate here is colder.

4) Possibly have the PCM checked out? the Vibe/Matrix had recall on the PCM which caused transmission issues, and my friend had fixed that for 1 of his Matrix before but the codes were completely different.

Please advise, I will be replying and adding my experience in detail for others who might have issues with P0741 once I resolve my issue.

@JeffKeryk any update on your niece's 2005 Corolla with P0741
 
Also check the wires to that connection where the plug connects to that spedo gear. I had a rabbit climb into my engine bay and eat through the wires and I also lost 4th gear. I ended up just having to splice the two wires and I was back up and running.
 

I don’t think this is it, I can swap that sensor from my 08 Corolla to confirm, it also doesn’t explain why a fluid change would make the P0741 prevalent.

And yes I have already done the research and watched this video.

The transmission in that video, still had issues after replacing that part
 
Well you've done your due diligence with fluid changes, filter, solenoids.

I would look into the ECM issue to see if yours may be affected.
 
@AKhan87 I've done nothing beyond services to my grand niece's Corolla; the $$ light has "mostly" been off. I don't see the car much as they live over the hill in Santa Cruz. The car runs fine. When it comes time for our CA bi-annual smog test, I might have to break out the check book.

Kinda disappointing that we buy Corollas their reliability but no car is immune. Luckily there is a great Toy/Lex only shop near here.
Wish I had solution for you but this is where I'm at.

Best of luck and I will follow your post.
 
Since you're in the Chicago area maybe take it to TCCN automotive to see if they can diagnose it for you. Should save you a lot of time, money and frustration. He has a YouTube channel by the name of the Car Care Nut and specializes in Toyotas/Lexus.
 
Since you're in the Chicago area maybe take it to TCCN automotive to see if they can diagnose it for you. Should save you a lot of time, money and frustration. He has a YouTube channel by the name of the Car Care Nut and specializes in Toyotas/Lexus.
I would have done that in a heartbeat as he helped save a transmission in the Matrix when another shop misdiagnosed it as an issue.

I have now moved back to Laramie, WY.
 
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