GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Pontiac 🢒 2001 🢒 Firebird 🢒 Body and Accessories 🢒 Body Control System 🢒 DTC P1514

Circuit Description

The powertrain control module (PCM) uses the following information in order to calculate an expected mass airflow (MAF) rate:

    • The throttle position (TP)
    • The barometric pressure (BARO)
    • The intake air temperature (IAT)
    • The engine RPM

The PCM compares this value to the MAF value, and the speed density calculation in order to verify the proper throttle operation.

Conditions for Running the DTC
    • Other electronic throttle control (ETC) DTCs are not present.
    • PCM processor DTCs are not present.
    • The engine is running and engine speed is more than 600 RPM.

Conditions for Setting the DTC

The PCM detects that the actual MAF and speed density is much more than the expected, or the calculated airflow rate.

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/Failure Records.

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

Inspect for the following:

    • The throttle blade for damage
    • A skewed cam sensor signal--Inspect for signals that are intermittently shorted to ground, causing a fluctuating RPM on the scan tool.

If the condition is intermittent, refer to Intermittent Conditions

Test Description

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

  1. Inspect the throttle body assembly. Manually move the throttle blade from closed to wide open throttle (WOT). You should not need to use excess force. The throttle blade should move smoothly through the full range and should return to a slightly open position.

  2. When the PCM detects a condition within the ETC system other DTCs may set due to the many redundant tests run continuously on this system. Locating and repairing 1 individual condition may correct more than 1 DTC. Keep this in mind when reviewing captured DTC info.

Step

Action

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

Are any other DTCs set?

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

    Caution: Turn OFF the ignition before inserting fingers into the throttle bore. Unexpected movement of the throttle blade could cause personal injury.

  1. Inspect the throttle body for the following conditions while modulating the throttle using the scan tool:
    2. • Loose or damaged throttle blade
    • Broken throttle shaft
    • Drive mechanism damage
  2. If any of these conditions exist, replace the throttle body of the TAC assembly. Refer to Throttle Body Assembly Replacement .

Did you find and correct the condition?

Go to Step 4

Go to Diagnostic Aids

4
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run, and pass?

Go to Step 5

Go to Step 2

5

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List

System OK