Eldorado V8-4.6L VIN Y (1994)
Throttle Position Sensor: Description and Operation
Throttle Position Sensor
Throttle Position Sensor (TPS)
PURPOSE
By monitoring the output voltage from the Throttle Position (TP) Sensor, the PCM can modify fuel delivery based on throttle valve angle. For
example; power enrichment occurs when the throttle angle approaches wide open throttle. The PCM senses changes in TP output which controls
fuel delivery. Acceleration enrichment occurs when the throttle angle increases abruptly, similar to an accelerator pump on a carbureted vehicle.
OPERATION
The TP Sensor 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. The sensor output signal is a DC voltage that varies with throttle angle. As the throttle valve angle changes, the voltage output of the TP
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.
DIAGNOSTIC NOTES
The TP can either be misadjusted, open, or shorted. If the sensor is open, the PCM will sense that the throttle is closed, and performance will be
reduced. This will normally set a trouble code P022. If the switch is shorted, the PCM will sense that the vehicle is at WOT, and a trouble code
P021 will be set. Intermittent problems can also set code P070. Once a trouble code is set, the PCM will substitute a value for the TP, and some
vehicle performance will return.
LOCATION
The TP sensor is on the top LH side of engine, on throttle assembly.
