Hi Guys,
 
I'm in the process of fitting an aftermarket ECU to my MR2. I have pretty much completed the wiring and confirming I have all inputs/outputs correctly wired.
 
Is anyone familiar with how the factory engine ecu and power steering ecu communicate? From what I understand, the engine ecu tells the power steering when the engine is running and according to the manuals, when ignition is on, there should be 1.5V or less between ground and PSCT pin. When running, the voltage should be 4.5v or more. I'm guessing the output should be grounded until the engine is started.
 
With the factory ECU unplugged, the pump runs when ignition is switched on.
 
Any help appreciated.
 
Regards,
James

Yeah all you have to do is connect the PSCT wire to an aux output from the aftermarket ECU, then set up the output to switch when the engine is running (I think the factory ECU checks for greater than 500rpm).

Thanks for clarifying robk.  The factory ecu must ground that pin prior to starting and then unground once engine has started (on prior, off when started)