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Discussion Starter · #1 ·
Hi,
My 2004 Sienna keeps throwing P0741 trouble code. I've changed the transmission filter, torque converter soleniod as well as used Toyota ATF Type T-IV transmission fluid. I can clear the code and drive for anywhere from 2 - 20 miles, and the code would come back. I also have a magnefine filter installed which I'm not sure if it could be causing/contributing to the issue. I believe it has a fail-open port which should allow fluid through if it's clogged.

Have you ever run across this issue? I'm scratching my head and hoping I could find a relatively inexpensive fix. I'd hate to have to go after the valve body or something costly.

Thanks!
 

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Could be a number of things but it’s related to slip in the torque converter. You might need a scanner with bidirectional capability unless you can double click into a lower level of codes. Top of mind are checking speed sensors and lockup solenoid function.

Sixto
‘04 LE FWD 198K miles
 

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Discussion Starter · #3 ·
Could be a number of things but it’s related to slip in the torque converter. You might need a scanner with bidirectional capability unless you can double click into a lower level of codes. Top of mind are checking speed sensors and lockup solenoid function.

Sixto
‘04 LE FWD 198K miles
Thanks. Any way to check speed sensor or lockup solenoid function? I saw the TSB about lockup function. I seem to be able to get through all the gears up and down just fine when driving. Is there a specific way to test both the speed sensor and lock up solenoid? Thanks
 

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As mentioned, you need a scanner that can read and compare speed sensor, more accurately rpm sensor, signals and have a reference document for what to expect under specific driving conditions. Such a scanner can tell you whether the solenoid is being signaled to activate or deactivate and a reference document will tell you something like what vehicle speed should be at a given rpm to confirm lockup is working.

If you’re perceptive, you can accelerate to fifth, hold speed steady then notice whether engine rpms drop a couple hundred rpms as the torque converter locks. If it does, my guess is an rpm sensor is bad. I don’t know if it’s a separate component or part of an assembly. There’s a transmission rpm sensor that attaches from the outside but I don’t know if that’s the suspect one. I’m pretty sure solenoids are available separately but quality ones aren’t cheap and they’re deep fried n the transmission. You have to remove the valve body which requires an immaculate workspace and a pounds-inches torque wrench. Not to mention dexterity working on components soaked in ATF.

Sixto
‘04 LE FWD 183K miles
 

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Discussion Starter · #5 ·
As mentioned, you need a scanner that can read and compare speed sensor, more accurately rpm sensor, signals and have a reference document for what to expect under specific driving conditions. Such a scanner can tell you whether the solenoid is being signaled to activate or deactivate and a reference document will tell you something like what vehicle speed should be at a given rpm to confirm lockup is working.

If you’re perceptive, you can accelerate to fifth, hold speed steady then notice whether engine rpms drop a couple hundred rpms as the torque converter locks. If it does, my guess is an rpm sensor is bad. I don’t know if it’s a separate component or part of an assembly. There’s a transmission rpm sensor that attaches from the outside but I don’t know if that’s the suspect one. I’m pretty sure solenoids are available separately but quality ones aren’t cheap and they’re deep fried n the transmission. You have to remove the valve body which requires an immaculate workspace and a pounds-inches torque wrench. Not to mention dexterity working on components soaked in ATF.

Sixto
‘04 LE FWD 183K miles
Thanks for the response! I'll give the driving a shot to 5th and hold. I'm pretty perceptive so hopefully I can figure that out. As for rpm sensor, I recall there's one that's relatively easy to reach. I'll check that too. And yeah, I've gone through solenoids before. Pretty easy to remove/replace for the most part. I get the cheapo ones from rockauto. I'm curious if the latest solenoid I got could have been bad. I doubt it though. Hate to pull the pan again! :)
 
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