DTC P1514 Throttle Body Performance

Circuit Description

The PCM uses the TP, the BARO, the IAT and the engine RPM in order to calculate an expected Mass Airflow rate. The PCM compares this value to the Mass Airflow value and the speed density calculation in order to verify the proper throttle operation.

Conditions for Setting the DTC

• DTCs P0601, P0602, P0606, P1515, P1516, P1517, P1518, P1624 are not set.
• DTCs P1120, P1220 and P1221 are not set at the same time or DTCs P1120 and P1220 are not set at the same time.
• Engine operates longer than 1 second.
• Engine speed is greater than 500 RPM.
• The PCM detects that actual airflow (MAF) and Speed Density is much greater than the expected (calculated) airflow rate.
• All above conditions met for less than 1 second.

Action Taken When the DTC Sets

• The PCM will illuminate the Malfunction Indicator Light (MIL) when this diagnostic runs and fails.
• The Reduced Engine Power message displays on the drivers information center.
• The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records.
• If no other TAC System DTCs are set, the TAC System operates in Reduced Engine Power mode, and this DTC will be stored. If certain TAC System DTCs are set at the same time, the TAC System either defaults to a more tightly restricted mode of operation if the TAC determines that limited safe operation is possible, or the TAC commands the engine to shut down.

Conditions for Clearing the MIL/DTC

• The PCM turns the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
• A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
• A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
• The PCM battery voltage is interrupted.

• Important

  The clear DTC info function may have to be performed twice in order to clear a Throttle Actuator Control System DTC.

  Clear the MIL/DTC information using a scan tool.

Diagnostic Aids

• Inspect the throttle blade for being broken, bent or missing.
• Inspect the TP sensor for proper installation. A sensor that is mis-aligned sets this DTC.
• For an Intermittent condition refer to Symptoms .
• If a repair is completed and the DTC was cleared using a scan tool on the same ignition cycle, the default action will not clear until an ignition cycle has occurred.
• When the TAC module detects a problem within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

DTC P1514 - Throttle Actuator Control (TAC) System MAF Performance