sbman
Supporting Vendor
I knew you had worked on this, and pinged you last spring as I headed down this path. This is really good info. Are you and EE? You seem to know your stuff on the electrical side. I am an ME who works for a test and measurement company with hundreds of EE's and software engineers. I have picked up enough over the years to be dangerous. At one point I had a four channel scope hooked up to the J80 as I drove around, verifying waveforms in the stock configuration.
This would be a lot easier if Toyota had shifted a manual transmission J80 to the US. Then it would be as simple as an ECU swap and would still be OBDII compliant. @landtank had an idea about using a 1996 or 1997 Supra / SC300 manual transmission ECU for a normally aspirated 2JZ-GE 3.0 inline six. I have two of those ECU's and was going to try that route to see if I could keep OBDII functionality.
But, before that, I will look through what you have above and see if there is a way to trick the stock ECU into not throwing error codes for the stock transmission not being there. Worth a shot, and I have all of the resistors, etc, that I need in labstock here at work.
Thanks,
Mike
I have a degree in electronics, but work in computers, but I've done a lot of low level programming for microcontrollers and that goes hand in hand with circuit design and done some of that as well.
One other thing I thought of is that if the ECU does decide to exercise a shift solenoid, it may draw too much current for the ECU to handle, IF it holds the solenoid ON. I'm not clear if it just pulses the solenoids or holds them. The description in the EWD seems to indicate that if you fool it into L it will drive the #1 shift solenoid full time. With solenoids the DC resistance when released is not the same as the 'hold' resistance which can be much higher and therefore lower current. I'd put 12V from a lab supply on your old transmission's #1 shift solenoid and see how much current it draws while 'holding'. Then you can use a relay to present a 12ohm resistor when the solenoid is not engaged (so the ecu sees the correct load) and a higher resistance switches in via the relay to lower the current when it is being driven by the ECU. Could even add a delay if the relay closing isn't slow enough to fool the ECU into thinking the 'fake solenoid' had reached it's hold point. That's all assuming the ECU can monitor the current on the solenoids, but I do think it probably has that ability so it can throw codes related to solenoids.