This is used when fitting a stand alone ecu to a Supra and replaces the factory Fuel Pump ECU
When running a larger fuel pump, Walbro 400/450/485 the factory ecu cannot take the load and will shut down.
If using a Walbro 520/525 then its advisable to change all the factory wiring.
Please specify if you would like the relay switched negatively or positively.