900 S Sedan L4-2290cc 2.3L DOHC (1994)
The control module is supplied with continuous information on the engine load (inlet air mass) through variations in the voltage applied to pin 7.
The mass air flow sensor is supplied with voltage from pin 87 of the main relay and is grounded through power ground G7P.
Pin 26 of the control module supplies signal ground to pin 2 of the mass air flow sensor.
Through the temperature compensation which is designed to take place when increased air flow is counteracted by higher current intensity through
the thermal resistor, the voltage drop across the resistor also increases and the voltage applied to pin 4 (and pin 7 of the control module) drops.
Accordingly, the voltage applied to pin 7 of the control module may vary from about 5 V at full load to about 1 V at idling speed. (When measured
with a BOB at full throttle and under no-load conditions, a reading of about 3 V will be obtained.)
In the event of a faulty or absent signal on pin 7 of the control module, the CHECK ENGINE lamp (MIL) lights up and the system goes into
Limp-Home mode.
