GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2006 🢒 Impala 🢒 Vehicle Control Systems 🢒 Vehicle DTC Information 🢒 DTC P1516, P2101, P2119, or P2176

DTC Descriptors

DTC P1516: Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance

DTC P2101: Throttle Actuator Position Performance

DTC P2119: Throttle Closed Position Performance

DTC P2176: Minimum Throttle Position Not Learned

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

TAC Motor Control 1

P1516, P2101, P2176

P1516, P2101, P2176

P1516, P2101, P2176

P1516, P2101, P2176

P1516, P2101, P2176

TAC Motor Control 2

P1516, P2101, P2176

P1516, P2101, P2176

P1516, P2101, P2176

P1516, P2101, P2176

P1516, P2101, P2176

Circuit/System Description

The engine control module (ECM) is the control center for the throttle actuator control (TAC) system. The ECM determines the drivers intent and then calculates the appropriate throttle response. The ECM achieves throttle positioning by providing a pulse width modulated voltage to the TAC motor. The TAC system uses the following circuits:

    • Motor control 1
    • Motor control 2

Two processors are used to monitor the TAC system data. Both processors are located within the ECM. Both processors monitor and share data to verify that the indicated throttle position is correct.

Conditions for Running the DTC

P1516

    • DTC P0068 or P0121 is not set.
    • The ignition is in the Run or Crank position.
    • The ignition voltage is more than 6.5 volts.
    • The engine is running, or the system is not in the Battery Save mode if the engine is not running.
    • DTC P1516 runs continuously when the above conditions are met.

P2101

    • DTC P0068 or P0121 is not set.
    • The ignition is in the Run or Crank position.
    • The system voltage is more than 11 volts.
    • The engine is running or the system is not in Battery Saver mode if the engine is not running.

P2119

    • The ignition is in the Unlock/Accessory, Run, or Crank position.
    • The ignition voltage is more than 5.23 volts.
    • The system is in the Battery Save mode.
    • DTC P2119 runs continuously when the above conditions are met.

P2176

    • The ignition is in the Run or Crank position.
    • DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135 is not set.
    • The system is in the minimum TP learn state.
    • The throttle is stable for more than 40 milliseconds.
    • DTC P2176 runs continuously when the above conditions are met.

Conditions for Setting the DTC

P1516

    •  The indicated throttle position does not match the predicted throttle position for more than 0.5 seconds.
        OR
    • The ECM detects a current draw of more than 9 amps on the motor circuits for more than 0.18 second.

P2101

The indicated throttle position does not match the predicted throttle position for more than 0.3 second.

P2119

The ECM detects that the throttle is unable to return to the default position after it is de-energized for more than 0.5 second.

P2176

The ECM detects that the minimum throttle position was not learned for more than 1.8 seconds.

Action Taken When the DTC Sets

P1516, P2101, and P2176

    • 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.

DTC P2119

    • The control module stores the DTC information into memory when the diagnostic runs and fails.
    • The malfunction indicator lamp (MIL) will not illuminate.
    • The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Failure Records.
    • The driver information center, if equipped, may display a message.

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.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

    •  Engine Control Module Connector End Views
    •  Engine Controls Connector End Views

Electrical Information Reference

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

Scan Tool Reference

Scan Tool Data List

Circuit/System Verification

With the ignition ON, use a scan tool to observe the throttle position (TP) sensor 1 indicated position. Throttle position should increase as pedal is applied and decrease as pedal is released. When no accelerator pedal activity is detected, The throttle position will return to the spring loaded default position.

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 blade that is binding open or closed
    • A throttle blade that is free to move open or closed WITHOUT spring pressure
  2. With the ignition ON, and the throttle body disconnected, measure for voltage between the TAC motor control 1 and 2 circuits and a good ground. The voltage should be 0 volts.
    3. ⇒If voltage is more than 0 volts, test the affected motor control circuit for a short to voltage or a faulty ECM.
  3. With the ignition ON, and the throttle body disconnected, probe the TAC motor control 1 and 2 circuits with a test lamp connected to B+. The test lamp should not illuminate.
    4. ⇒If test lamp illuminates, test the affected motor control circuit for a short to ground.
  4. Ignition OFF, allow sufficient time for the ECM to completely power down.
  5. Connect a DMM between the TAC motor control 1 circuit and ground.
  6. Using the 1 ms Peak Min/Max feature set to the 40 V scale, measure the voltage while turning ON the ignition. The max voltage should be within 0.5 volt of B+.
    7. ⇒If the voltage is not within 0.5 volt of B+, test the TAC motor control 1 circuit for an open, high resistance, or for a faulty ECM.
  7. Turn OFF the ignition.
  8. Connect a DMM between the TAC motor control 2 circuit and ground.
  9. Using the 1 ms Peak Min/Max feature set to the 40 V scale, measure the voltage while turning ON the ignition. The max voltage should be within 0.5 volt of B+.
    10. ⇒If the voltage is not within 0.5 volt of B+, test the TAC motor control 2 circuit for an open, high resistance, or for a faulty ECM.
  10. If all circuits test normal, replace the throttle body.

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

Repair Verification

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.