Secondary Air Injection (SAI) Pump Relay The secondary air injection pump relay, coloured pink for identification, is located in the E-Box. The engine control module (ECM) is used to control the operation of the SAI pump via the SAI pump relay. Power to the coil of the relay is supplied from the vehicle battery via the main relay and the ground connection to the coil is via the ECM. Secondary Air Injection Non Return Valve The secondary air injection non return valve is located on the steel air delivery tube at the front of the engine. The valve is controlled by the ECM via the vacuum vent solenoid.