Subaru Fuel Pump Controller

[JamesD]

On the OEM Subaru fuel pump voltage controllers pins 8 and 9 connect to the ECU. Most people seem to just remove the controller and run relay only on the fuel pump, but I'd like to keep it for now if possible.

Does anyone know how the OEM ECU supplies the PWM signal? I'm assuming 5V and ground switched PWM, but really have no idea.

Also, any ideas on the PWM frequency?

Sorry for the dumb question; thanks in advance! This is for an '05 USDM Legacy GT, unfortunately I don't have a car here to scope). I can grab a P/N later tonight, but AFAIK the later Legacy, WRX, etc. all have the same pinout.