P1516

DTC P1516, P2101, P2119, or P2176

Diagnostic Instructions

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

DTC Descriptors
DTC P1516 00
- Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance

DTC P2101 00
- Throttle Actuator Position Performance

DTC P2119 00
- Throttle Closed Position Performance

DTC P2176 00
- Minimum Throttle Position Not Learned

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 sensors 1 and 2 to determine the actual throttle valve position.

Conditions for Running the DTC

P1516 00 or P2101 00
* DTC P1682 00 is not set.
* The engine is running.
* The ECM has learned the minimum throttle position.
* The ignition voltage is greater than 6 volts and reduced power is not active.
* DTCs P1516 00 and P2101 00 run continuously when the above conditions are met.

P2119 00
* DTCs P0121 00, P0122 00, P0123 00, P0222 00, P0223 00, P0641 00, P0651 00, P0697 00, P06A3 00, or P2135 00 are not set.
* The ignition voltage is greater than 8 V.
* DTC P2119 00 runs when the ignition is turned to the OFF position, when the above conditions are met.

P2176 00
* The ignition voltage is greater than 8 V.
* DTC P2176 00 runs once per ignition cycle when the above conditions are met.

Conditions for Setting the DTC

P1516 00 and P2101 00

The ECM detects the difference between the actual throttle position, and the desired position is greater than 7.5% for 30 s.

P2119 00

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

P2176 00

The ECM detects that both throttle position sensors were greater than 0.95 V during the minimum learn procedure.

Action Taken When the DTC Sets

P1516 00, P2101 00, or P2176 00
* DTCs P1516 00, P2101 00, and P2176 00 are Type A DTCs.
* The ECM commands the TAC system to operate in a reduced engine power mode.
* A message center or an indicator displays Reduced Engine Power.
* Under certain conditions the control module commands the engine OFF.

P2119 00

DTC P2119 00 is a Type C DTC.

Conditions for Clearing the DTC

* DTCs P1516 00, P2101 00, and P2176 00 are Type A DTCs.
* DTC P2119 00 is a Type C DTC.

Diagnostic Aids

* A high resistance condition with the throttle position sensor circuits could cause DTCs P1516 00, P2101 00, P2119 00, or P2176 00 to set.
* 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 ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Throttle Actuator Control (TAC) System Description (Throttle Actuator Control (TAC) System Description)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information

Circuit/System Verification

1. Ignition ON, observe the DTC information with a scan tool. Verify DTCs P0121 00, P0122 00, P0123 00, P0222 00, P0223 00 or P2135 00 should not set.

• If any of the DTCs are set refer to DTC P0121-P0123, P0222, P0223, or P2135 (P0121) for further diagnosis.

2. 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 P1516 00, P2101 00, P2119 00, or P2176 00 should not set.
3. Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times. DTCs P1516 00, P2101 00, P2119 00, or P2176 00 should not set.
4. Engine idling, observe the TAC Command parameter with a scan tool. The reading should display greater than 0%.
5. Operate the vehicle within the conditions for running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the freeze frame/failure records data.

Circuit/System Testing

1. Inspect the Q38 Throttle Body for the following conditions:

* 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 any condition is found, replace the Q38 Throttle Body.

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

2. Ignition OFF, disconnect the harness connector at the Q38 Throttle Body.
3. Ignition ON, test for greater than 9 V on the motor control 1 circuit terminal A and motor control 2 circuit terminal B.

• If less than the specified range, test the appropriate motor control circuit for a short to ground, or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module.

4. Ignition ON, probe the Q38 Throttle Body motor control 1 circuit terminal A and Q38 Throttle Body motor control 2 circuit terminal B with a test lamp connected to ground. Verify the test lamp does not illuminate.

• If the test lamp illuminates, test the appropriate Q38 Throttle Body motor control circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module.

5. Set the DMM to AC hz on the 400 mV scale. Engine idling, test for greater than 2 000 AC hz between the Q38 Throttle Body motor control circuits listed below and ground while commanding the Engine Speed to 1 950 RPM with a scan tool.

* Q38 Throttle Body motor control 1 circuit terminal A
* Q38 Throttle Body motor control 2 circuit terminal B

• If less than the specified value, replace the K20 Engine Control Module.

6. If all circuits and connections test normal, replace the Q38 Throttle Body.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Throttle Body Assembly Replacement (1.6L LDE, LXV, 1.8L 2H0, and LUW) (Removal and Replacement)
* Control Module References (Programming and Relearning)for ECM replacement, setup, and programming.