Fleetwood FWD V8-300 4.9L (1993)
Throttle Position Sensor: Description and Operation
Throttle Position Sensor (TPS)
Throttle Position Sensor (TPS)
The Throttle Position Sensor (TPS) is a three wire sensor or potentiometer which has a five volt reference, a reference ground, and a output signal from
the sensor to the PCM/ECM. The sensor output signal is a DC voltage that varies with throttle angle. As the throttle valve angle changes, the voltage
output of the TPS also changes. At a closed throttle position, the output of the TPS is low. As the throttle plate opens, the output voltage increases so
that, at wide-open throttle, the output voltage should be approximately 5 volts.
By monitoring the output voltage from the TPS, the PCM/ECM can modify fuel delivery based on throttle valve angle. For example; power enrichment
occurs when the throttle angle approaches wide open throttle. The PCM/ECM senses changes in TPS output which controls fuel delivery. Acceleration
enrichment occurs when the throttle angle increases abruptly, similar to an accelerator pump on a carbureted vehicle.
The TPS can either be misadjusted, open, or shorted. If the sensor is open, the PCM/ECM will sense that the throttle is closed, and performance will be
reduced. This will normally set a trouble code E022. If the switch is shorted, the PCM/ECM will sense that the vehicle is at WOT, and a trouble code
E021 will be set. Intermittent problems can also set code E070. Once a trouble code is set, the PCM/ECM will substitute a value for the TPS, and some
vehicle performance will return.
