Circuit Description
The throttle body assembly contains 2 throttle position (TP) sensors.
The TP sensors are mounted to the throttle body assembly and are not serviceable.
The TP sensors provide a signal voltage that changes relative to throttle blade angle.
The engine control module (ECM) supplies each TP sensor with a 5-volt reference circuit,
a low reference circuit, and a signal circuit.
The TP sensors have opposite functionality. TP sensor 1 signal voltage
decreases from above 4 volts at idle to below 1 volt at wide open throttle
(WOT). TP sensor 2 signal voltage increases from below 1 volt at idle
to above 4 volts at WOT.
If the ECM detects TP sensor 1 signal voltage is too low or too high,
this DTC sets.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P0120 Throttle Position (TP) Sensor 1 Circuit
Conditions for Running the DTC
| • | DTCs P0341, P0351, P0601, P0602, P0603, P0604, P0606, P0607 are
not set. |
| • | The ignition is ON, with the engine OFF, or the engine is operating. |
| • | The ignition 1 voltage is more than 5.23 volts. |
| • | DTC P0120 runs continuously when the above conditions are met. |
Conditions for Setting the DTC
| • | The ECM detects the TP sensor 1 signal voltage is less than 0.275 volts
for less than 1 second. |
| • | The ECM detects the TP sensor 1 signal voltage is more than 4.73 volts
for less than one 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. |
Diagnostic Aids
| • | Use the
J 35616 Connector Test Adapter
Kit for any test that requires probing the ECM harness connector or a component harness
connector. |
| • | If there is a condition with the TP sensors, the ECM defaults to reduced
power mode for the entire ignition cycle, even if the condition is corrected. |
Test Description
The number below refers to the step number on the diagnostic table.
-
This step verifies that other DTCs are set.
