900 S Convertible L4-2290cc 2.3L DOHC EFI (1997)
Throttle Position Sensor: Description and Operation
The position sensor consists of a potentiometer connected to the throttle spindle.
The sensor is supplied with 5 V from pin 59 and grounded via pin 71 of the control module. The voltage from the sensor is connected to pin 73 of the
engine control module and is proportional to the throttle opening.
The voltage is approx. 0.5 V during idling and approx. 4.5 V at wide open throttle. The engine control module uses the voltage from the sensor to
identify idling, partly open throttle and wide open throttle. The engine control module uses a special ignition control matrix to adjust idling speed.
The closed loop is disconnected at wide open throttle.
A richer mixture is used during acceleration and a weaker mixture during deceleration.
Should the sensor fail to work or in the event of a break in the circuit (no continuity), the control module will use the engine load calculated with the
mass air flow sensor as a substitute value.
Throttle Position Signal
The control module sends out a throttle position signal from pin 38 to the transmission control module. This is a 100 Hz PWM signal with a pulse ratio
of 90% at idling speed (about 1.2 V) and about 90% at wide open throttle (about 12 V).
