GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2008 🢒 LaCrosse 🢒 Safety and Security 🢒 Supplemental Inflatable Restraints 🢒 DTC P1516

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 Descriptor

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

Circuit/System Description

The commanded throttle position (TP), based on accelerator pedal position (APP), is compared to the actual throttle position. The TP values should be within a calibrated range of each other. The throttle actuator control (TAC) module monitors the commanded and the actual throttle position. If the TAC module detects that the commanded and actual throttle positions are not within a calibrated range of each other, the TAC module or the powertrain control module (PCM) cannot determine throttle position, or if both TP sensors are invalid, a message is sent to the PCM across serial data and DTC P1516 is set.

Conditions for Running the DTC
    • The ignition is in the Crank or Run position with the engine OFF.
    • The system voltage is more than 5.23 volts.
    • The system is not in Battery Saver mode.
    • The communication between the TAC module and the PCM must be valid.
    • The DTC runs continuously when the above conditions are met.

Conditions for Setting the DTC

The TAC module detects the commanded and the actual throttle positions are not within a calibrated range of each other.

Action Taken When the DTC Sets
    • DTC P1516 is a Type A DTC.
    • The control module commands the TAC system to operate in Reduced Engine Power mode.

Conditions for Clearing the DTC

DTC P1516 is a Type A DTC.

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 P2108 is also set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  2. If DTC P0120 and P0220 are also set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  3. If DTC U0107 is also set with P0120, P0220, P2120 or P2125, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  4. If DTC U0107 only is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle.
  5. Ignition OFF for 30 seconds.
  6. Ignition ON, observe the TP Sensor 1 and TP Sensor 2 parameters while moving the accelerator pedal to the fully applied position, and back to the at-rest position. The TP Sensor parameters should increase to 100 percent as the accelerator pedal is moved to the fully applied position, and back tot he at-rest position as the accelerator pedal is released.
  7. 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