[b3lha]

Originally Posted by Nomake Wan

Now sadly I don't know enough about the hardware we're dealing with to be 100% sure about my translation of the final paragraph. But HOLY CRAP GUYS, YOU HAVE TO READ IT!!! IT'S AMAZING!!!!! Maybe this will solve the problems with the feedback coming in so slowly!!

Yes!!! That is very useful information. Thanks for the translation.
The ASCII mode comms routine is at FCDD in the SVX code. The commands are 12, 7F and 20 exactly as per Kashima-san's website. I'll give it a try later and see if it works at the higher baud rate. I'll also check what he said about the rate not returning to normal, but at first glance it looks like the baud rate is reset at the start of each comms routine.
If it doesn't work then there may be another way: At the start of each comms routine there is a flag (bit 6 of location 11CF), which indicates which baud rate is currently in use. It checks the flag to see whether it needs to reset the baud rate. Perhaps by switching to the ASCII mode and then clearing the flag we can make it skip the reset when it gets to the Normal mode routine.

Originally Posted by Nomake Wan

EDIT: I thought about that some. It makes sense. Also, it should be noted that the TCU does NOT have an ASCII interpretation mode. How do I know? Look at the command that Kashima-san gives for "STOP" in ASCII mode. On the ECU, that works even when receiving binary data (I've just typed "12" into the comm tool and it stopped the stream). On the TCU, sending it only "12" has NO effect at all. You have to type "12000000" for it to stop. So I guess the ECU is the only computer in the car with an alternate mode... which means it's probably the only one we can mess around with the baud rate on.

You are right, but not for that reason. Even in the binary mode, the ECU only requires a single "12" to make it stop. If I understand you right, you sent the single 12 at 1936 baud (binary mode) not 4808 baud (ASCII mode)?
I had a quick scan through the TCU code but I can't see anything that looks like an ASCII mode routine.