P0121
CIRCUIT DESCRIPTIONThe Throttle Position (TP) sensor is used by the Powertrain Control Module (PCM) to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with three circuits, a 5-volt reference circuit, a low reference circuit, and a signal circuit. The PCM provides the TP sensor with a 5-volt reference circuit and a low reference circuit. Rotation of the TP sensor rotor from the closed throttle position to the Wide Open Throttle (WOT) position provides the PCM with a signal voltage from less than 1.0 volt to greater than 4 volts through the TP sensor signal circuit. When the conditions for running this DTC are met, the PCM will use the MAP sensor to determine if the predicted operating range of the TP Sensor is correct. A skewed Manifold Absolute Pressure (MAP) sensor may cause this DTC to set and should be tested for proper operation if the TP sensor is determined to be operating properly and this DTC continues to set.
CONDITIONS FOR RUNNING THE DTC
^ DTCs P0106, P0107, P0108, P0122, P0123, P1106, P1107, P1121, P1122 are not set.
^ Engine running for greater than 2 minutes.
^ ECT is greater than 75°C (167°F).
^ MAP reading is less than 50 kPa for a TP sensor skewed high test.
^ MAP reading is greater than 70 kPa for a TP sensor skewed low test.
^ MAP is steady for 5 seconds or more.
CONDITIONS FOR SETTING THE DTC
^ The TP sensor reading is greater than a predicted value when the MAP is below 50 kPa.
^ The TP sensor reading is less than a predicted value when the MAP is above 70 kPa.
^ The above conditions are present for 10 seconds.
ACTION TAKEN WHEN THE DTC SETS
^ First failure:
- The MIL is not turned ON.
- A DTC is stored in memory under Failed Last Test.
- The Failure Records are stored.
^ Second consecutive drive cycle with a failure:
- The MIL is turned ON.
- A DTC is stored in memory under history.
- The Freeze Frame data is stored.
- The Failure Records are stored.
CONDITIONS FOR CLEARING THE MIL/DTC
^ The control module turns OFF the Malfunction Indicator Lamp (MIL) after the third consecutive trip the diagnostic has run and passed.
^ The history DTC will clear if the fault conditions have not been detected for 40 warm-up cycles.
^ A scan tool can be used to clear DTC information.
DIAGNOSTIC AIDS
Inspect for the following conditions:
^ Skewed MAP signal-A skewed MAP signal may cause the PCM to incorrectly determine the TP sensor is out of range. Inspect for an unusually low or high MAP reading.
^ If the DTC is determined to be intermittent or if the TP sensor system is still suspect, refer to DTC P1121 and/or Intermittent Conditions. P1121 Intermittent Conditions
TEST
