Closing the loop on this - the used ECU was installed and programmed by dealer and few weeks later confirmed to be fully operational. We then did a reset of the engine and transmission ECU and the car is behaving now. A lot of headache to get here...

 

Glad it's fixed. Sorry they wouldn't do it under warranty as they should have.

 

Good to know. I usually look for responses from you as you always seem to have good insight. Do you work for Toyota?

 

yeah, pretty incredible...

 

No, just an Infosec guy who has done a lot of wrenching for a long time.

 

I’m currently in the market for a 2016 GSF to replace my GS350 F Sport. I wasn’t aware of a potential TVD failure on these cars, and a part failing that’s worth half the cars value is slightly concerning. Thanks!

 

I'm not sure I'd characterize the situation this way. There are lots of things to potentially fail that are expensive. My 1992 GTS Celica's chassis made a click every time I really put a cornering load on it. Very few people would even notice this, much less think it was a problem. It was undoubtedly a bad spot weld or two, and only someone doing what I was doing with the car would notice it. I'm in the less than 1% club there.

This particular issue just took too long to positively identify. I ran a Techstream all ECU/ECM health check on this car while we were addressing a transmission shifting issue and there were a number of oddities, but all of them except this one cleared easily or were easily explained and also cleared. The only "solution" from the troubleshooting tree in TIS was replace the TVD ECU which seems very odd.

My IS F just had a weird event where it set some DTCs related to excessive long term fuel trim (LTFT). I stepped through the diagnostic tree in TIS to better understand what's happening, and if I were a dealership mechanic, I'd've been telling the customer the ECM is bad. This completely ignores the simple fact all the O2 sensors are almost 15 years old with almost 200k miles on them. IMHO, replacing the O2 sensors should be first, and fixing the cracked exhaust header on the driver's side should also be right up there, but if I were following the factory service manual, I'd be replacing the ECM and (I believe) still facing the same issue. Don't misunderstand me, the manual can be very valuable in understanding where to start looking, but it can't take all the secondary factors into account. This is where experience and understanding of how these things work makes a huge difference in the troubleshooting process. Not only that, but I cleared these DTCs and they have not returned, nor are they pending.

Saying this thread helped someone dodge a bullet is a real stretch.

 

Even with the list of parts still sitting in my garage I have yet to install on my ISF I was considering/lowkey window shopping a GSF. But this whole time I didn't know TVD wasn't an option on them like the RCF, and I actually didn't know the TVD had potential issues even to the magnitude these few guys went through. That kind of gives me pause now