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 0.15-0.55 volts at 0 percent throttle to 4.45-4.85 volts
at wide open throttle. DTC P0123 sets when the TP sensor signal voltage at
the PCM is above the calibrated voltage value.
DTC Parameters
DTC P0123 will set if:
| • | The TP sensor voltage is greater than 4.86 volts for 14 seconds. |
| • | No MAP sensor DTCs have been set |
| • | The TP sensor voltage is greater than 3.91 volts for 14 seconds. |
| • | The engine is running less than 1500 RPM. |
| • | The MAP is less than 60 kPa (9 psi). |
| • | No MAP sensor DTCs have been set. |
DTC P0123 diagnostic runs continuously with the engine running.
P0123 is a type B DTC.
Diagnostic Aids
To locate an intermittent problem, use the scan tool to monitor the TP sensor
voltage with the ignition ON and the engine OFF. Wiggling the 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.
Important: The A/C pressure sensor, fuel tank pressure sensor, and TP sensor are all tied
to the same 5 volt reference source.
An intermittent short in the TP sensor can cause this DTC to set. Use the scan
tool to monitor the TP sensor as the accelerator pedal is slowly depressed. The voltage
should change smoothly from 0.35 volts at 0 percent throttle, to 4.65 volts
at wide open throttle, 0.15-0.55 volts.
