GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Epica 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC P0638, P2111, P2112, or P2119

DTC P0638, P2111, P2112, or P2119 w/Throttle Actuator Control

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 provide an overview of each diagnostic category.

DTC Descriptors

DTC P0638: Throttle Actuator Control (TAC) Command Performance

DTC P2111: Throttle Actuator Control (TAC) Throttle Valve Stuck Open

DTC P2112: Throttle Actuator Control (TAC) Throttle Valve Stuck Closed

DTC P2119: Throttle Closed Position Performance

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

Motor Control 1

P0638

P0638

P0638

--

--

Motor Control 2

--

P0638

P0638

--

--

Circuit/System Description

The engine control module (ECM) controls the throttle valve by applying a varying voltage to the control circuits of the throttle actuator control (TAC) motor. The ECM monitors the duty cycle that is required to actuate the throttle valve. The ECM monitors the throttle position (TP) sensors 1 and 2 to determine the actual throttle valve position.

Conditions for Running the DTCs

DTC P0638

    • The ignition is ON.
    • The DTC runs continuously when the above condition is met.

DTC P2111, P2112, and P2119

    • The engine is running.
    • The DTCs run continuously when the above condition is met.

Conditions for Setting the DTC

DTC P0638

The ECM detects the difference between the actual throttle position, and the desired position is greater than a calibrated amount for 5 seconds.

DTC P2111

The ECM detects the throttle blade is stuck open for 1 second.

DTC P2112

The ECM detects the throttle blade is stuck closed for 1 second.

DTC P2119

The ECM detects that the throttle blade did not return to the default position, during power down, within a calibrated amount of time

Action Taken When the DTC Sets

DTCs P0638, P2111, P2112, and P2119 are Type A DTCs.

Conditions for Clearing the DTC

DTCs P0638, P2111, P2112, and P2119 are Type A DTCs.

Diagnostic Aids

Inspect for a condition in which the throttle valve may have been held open. For example, ice may have formed in the throttle bore causing the throttle valve not to close.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls 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

    •  Scan Tool Data List
    •  Scan Tool Data Definitions
    •  Scan Tool Output Controls

Circuit/System Verification
  1. Ignition ON, observe the scan tool DTC information parameter. Verify DTCs P0121, P0122, P0123, P0221, P0222, or P0223 are not set.
    2. ⇒If any of the DTCs are set, refer to DTC P0121, P0122, P0123, P0221, P0222, or P0223 for further diagnosis.
  2. Start the engine and rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times. DTCs P0638, P2111, P2112, or P2119 should not set.
  3. Ignition ON, observe the throttle valve while commanding the TAC motor with the scan tool. The throttle valve should move smoothly from close to open and back to close. DTCs P0638, P2111, P2112, or P2119 should not set.
  4. Operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

Circuit/System Testing
  1. Inspect the throttle body for the following conditions:
    2. • A throttle blade that is not in the rest position
    • A throttle valve that is binding open or closed
    • A throttle valve that opens or closes without spring pressure
    ⇒If a condition is found, replace the throttle body.

    Important: Disconnecting the throttle body harness connector causes additional DTCs to set.

  2. Ignition OFF, disconnect the harness connector at the throttle body.
  3. Install fused jumper wires between the throttle body and harness connector of the following circuits:
    4. • Low reference circuit
    • 5-volt reference circuit
    • TP sensor 1 or TP sensor 2 signal circuit
  4. Ignition ON, test for less than 0.5 volts on the motor control 1 and motor control 2 circuits.
    5. ⇒If greater than the specified value, test the appropriate motor control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

    Important: The scan tool TAC motor command is disabled, if multiple TP sensor or TAC circuit DTCs are set.

  5. Ignition OFF, command the TAC motor with the scan tool, while measuring the voltage of the TAC motor control 1 circuit and TAC motor control 2 circuit at the harness connector.
    6. ⇒If the voltage changes between 0.0 volts to greater than 10.5 volts on both circuits, replace the throttle body.
    ⇒If the voltage changes between 0.0 volts to less than 10.5 volts on either circuit, test for an open or a short to ground in the appropriate TAC motor control circuit.
    ⇒If the circuits test normal, replace the ECM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Throttle Body Assembly Replacement
    •  Control Module References for ECM replacement, setup, and programming