P0121

CIRCUIT DESCRIPTION
The Throttle Position (TP) sensor is used by the PCM to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with three circuits; 5 volt reference, low reference, and signal. 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 4.0 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 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 P0107, P0108, P0122, P0123, P1106, P1107, P1121, or P1122 are not set.
^ No other active TP sensor or MAP sensor DTCs are 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 0.5 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 5 seconds.

ACTION TAKEN WHEN THE DTC SETS
^ The PCM will illuminate the Malfunction Indicator Lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
^ The PCM will store conditions which were present when the DTC set as Freeze Frame/Failure Records data.

CONDITIONS FOR CLEARING THE MIL/DTC
^ The PCM will turn OFF the Malfunction Indicator Lamp (MIL) during the third consecutive trip in which the diagnostic has run and passed.
^ The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
^ The DTC can be cleared by using a scan tool.

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 the TP sensor system is still suspect, refer to DTC P1121 and/or Symptoms - Computers and Control Systems in Symptoms. P1121 Symptom Related Diagnostic Procedures

TEST

Steps 1-3:

Steps 4-15: