You are sure to be correct Pete. Adding 5v to that pin would be pi$$ing in the breeze.
I have a new plan that takes account of Mike's advice that will work for UK cars. [The US cars can use a variant of it also if they want]
Using the Econ switch I will feed the 5v line to the TPS pin of the TCU. To stop the 5v going back up the line to the ECU and causing problems, I will be adding an in-line diode to the connection so the 5v can only go one way to the TCU, and not feed back to the ECU.
In addition I will put an interruptor in the line, so the TPS pin is reading 0-5v rather than a steady 5v. This will ensure Power mode is permanently on. I am not sure what Mike means by a "555 timer", but if it is simple and easily installed, that is what I will use. Something like what breaks the circuit for the indicators or the hazard lights would do nicely, but of course no way I would accept the clicking. An inaudible device would have to be found.
I find it interesting that in the JDM TCU that has switchable Power mode, the speed sensor two input is a 5v square wave. Connecting this square wave internally in the box to the TPS input would have the same effect as described above. I wonder if this is what is done internally in the JDM box to turn Power mode on, when pin 4 is earthed?
We will never know, I suppose. Anyway, I now see a way forward. I will rewire it when the new gearbox is in. I don't want to do any messing with the wires until I am sure all the readings and input/outputs are in the correct range. That way I won't compound a felony.
Joe
