Circuit Description
The throttle position (TP) sensor is a potentiometer that varies resistance according to changes in the throttle plate position. The PCM measures the signal voltage from the TP sensor, which is a reduced value of the PCM 5 volt reference. The voltage ranges from 0.35 (+/-0.2) volts at 0% throttle to 4.65 (+/-0.2) volts at side open throttle. DTC P0123 sets when the TP sensor signal voltage at the PCM is above the calibrated voltage value.
Conditions for Setting the DTC
DTC P0123 will set if:
| • | TP sensor voltage is greater than 4.86 volts for 14 seconds |
| • | Engine is running |
| • | No MAP sensor DTCs have been set |
OR
| • | TP sensor voltage is greater than 3.91 volts for 14 seconds |
| • | Engine is running and less than 1500 RPM |
| • | MAP is less than 60 kPa |
| • | No MAP sensor DTCs have been set |
DTC P0123 diagnostic runs continuously with engine running.
P0123 is a (type B) DTC
Diagnostic Aids
To locate an intermittent problem, us the scan tool to monitor the TP SENSOR voltage with the ignition On, engine Off. Wiggling wires while watching for a change in the TP SENSOR voltage may locate the area where an open or short to voltage in the wiring could lie.
An intermittent short in the TP sensor can cause this DTC to set. Use Scan tool to monitor TP SENSOR as the accelerator pedal is slowly depressed. The voltage should change smoothly from 0.35 volts at 0% throttle, to 4.65 volts at wide open throttle (+/-0.2 volts).
Important: The A/C pressure sensor, fuel tank pressure sensor and TP sensor are all tied to the same 5 volt reference source.
DTC P0123
