GM Service Manual Online
For 1990-2009 cars only

Diagnostic Instructions

    •  Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    •  Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P2107: Throttle Actuator Control (TAC) Module Internal Circuit

DTC P2108: Throttle Actuator Control (TAC) Module Performance

Circuit/System Description

The throttle actuator control (TAC) module contains data, which is essential for proper TAC system operation. The TAC module continuously checks the integrity of this data. If the TAC module detects a fault with electrically erasable programmable read only memory (EEPROM), the TAC module detects a low voltage while the voltage on the powertrain control module (PCM) is not low, or the TAC module detects the vehicle ID from TAC module does not agree with the vehicle ID from the PCM, DTC P2107 sets. If the TAC module is unable to write or read data to and from random access memory (RAM), the TAC module is unable to correctly read data from the flash memory, or an internal TAC module processor fault is detected, DTC P2108 sets.

Conditions for Running the DTC

P2107

    • The ignition is in the Run or Crank position.
    • DTC P0606, P2108 or U0107 is not set.
    • The DTCs run continuously when the above conditions are met.

P2108

    • The system voltage is more than 5.23 volts.
    • The ignition is in the Crank or Run position.
    • The communication between the TAC module and the PCM must be valid.

Conditions for Setting the DTC

P2107

The TAC module detects low voltage, a fault with the EEPROM, or the vehicle ID recorded in the TAC module does not match the vehicle ID recorded in the PCM.

P2108

The TAC module determines that an internal data test did not pass.

Action Taken When the DTC Sets

    • DTCs P2107 and P2108 are Type A DTCs.
    • The control module commands the TAC system to operate in Reduced Engine Power mode.

Conditions for Clearing the DTC

DTCs P2107 and P2108 are Type A DTCs.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Throttle Actuator Control (TAC) System Description

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

  1. If DTC P2119 is set with DTC P2107, refer to DTC P2119.
  2. Operate the vehicle within the Conditions for Running the DTC, or within the conditions that you observed from the Freeze Frame/Failure Records data.

Circuit/System Testing

Replace the throttle body assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Throttle Body Assembly Replacement