Engine Controls and Fuel
DTC P0120
Circuit Description
The throttle position (TP) sensors 1 and 2 are located within the throttle body assembly. Each sensor has the following circuits:
* A 5-volt reference circuit
* A low reference circuit
* A signal circuit
The TP sensor provides the engine control module (ECM) with a signal voltage proportional to the throttle plate movement. The TP sensor 1 signal voltage at closed throttle is near the 5-volt reference and decreases as the throttle plate is opened. The TP sensor 2 signal voltage at closed throttle is near the low reference and increases as the throttle plate is opened. When TP sensor 1 signal voltage is not within the predicted range, this DTC will set.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0120 Throttle Position (TP) Sensor 1 Circuit
Conditions for Running the DTC
* The ignition switch is in the crank or run position.
* DTC P0641 is not set.
* The ignition voltage is greater than 2.25 volts.
* DTC P0120 runs continuously when the above conditions are met.
Conditions for Setting the DTC
TP sensor 1 voltage is less than 0.27 volt or more than 4.67 volts for more than 0.5 second.
Action Taken When the DTC Sets
* The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
* The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame and/or the Failure Records.
* The control module commands the TAC system to operate in the Reduced Engine Power mode.
* A message center or an indicator displays Reduced Engine Power.
* Under certain conditions the control module commands the engine OFF.
Conditions for Clearing the MIL/DTC
* The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
* A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
* A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
* Clear the MIL and the DTC with a scan tool.
Test
