Quote:
Originally Posted by TrickyT
Hey, nice install Adam. Great OEM look to it. And nice writeup too - very thorough.
Probably true, but really hard to say for sure. As you know, the A343F is electronically controlled by the ECU. The FSM documents at least most, maybe all, of the sensors and switches that the ECU uses for input for controlling AT operation. Obvious things are throttle position, vehicle speed, and shifter position. The EWD mentions coolant temperature too, but doesn't say how it uses this input for AT control. The ATF temperaure sensor isn't mentioned. My point is that it's hard to know with certainty that the ECU doesn't also use ATF temp in some way too. For sure it uses it to turn the combination meter idiot light on/off, but it could consider ATF temp when deciding to lock/unlock the torque converter too, since that would be an obvious way to lower/raise ATF temperature.
Without looking at the computer program that runs in the ECU, we'll never know for sure. I think your conclusion about the ATF temp sensor only controlling the idiot light is reasonable, but you can't be 100% certain just because the Toyota manuals don't talk about it.
|
Thanks! What you say is definitely true, it is impossible to tell if the sensor is interconnected with any other aspect of the automatic transmission function without talking to the engineer who designed the ECU. I will edit my original post to reflect that.
I will be keeping a close eye and ear on the transmission with regards to any difference in operation. I know from reading here and from discussing it with the guys in the Lexus shop that the transmission won't shift into overdrive before coolant temperature reaches a certain point (55C IIRC) in order to get the engine up to operating temperature faster. I haven't found anything with any connection to the ATF temperature in all of my research or discussions (not to say that there isn't some info still out there that I have yet to see). I also place a good deal of faith in the knowledge and info I got from my friend (the Lexus Head technician). He knows that my priorities are aimed at keeping all required OEM systems intact and not compromising anything when adding a modification such as this. I guess what I am saying is that I am quite comfortable with removing the OEM ATF temperature sender to add in a temperature gauge. From what I have learned thus far, it will not affect the operation of the transmission (my opinion only!).
I will report back if I ever find anything out of the ordinary.
