GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The engine control module (ECM) contains data, which is essential for proper throttle actuator control (TAC) system operation. The ECM continuously checks the integrity of this data. If the ECM detects a fault in the TAC system, the ECM disables the TAC motor. The accelerator pedal position (APP) sensor will have no affect on the throttle position (TP) and the throttle will remain in the default position. If the ECM detects an internal fault or any fault that causes the throttle to be at the default position and the engine does not respond within the predetermined limits, DTC P2108 sets.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The difference between the calculated and the actual throttle position is more than a predetermined value.

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.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check-Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle in Vehicle DTC Information

2

Are any other DTCs  set?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Go to Step 3

3

Replace the ECM. Refer to Engine Control Module Replacement .

Did you complete the replacement?

 

Go to Step 4

 

4

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 60 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

--

Go to Step 2

Go to Step 5

5

Observe the Capture Info with a scan tool.

Are there any DTCs that have not been diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

System OK