Diagnostic Instructions

DTC Descriptors

DTC P1516: Throttle Actuator Control Position Range/Performance

DTC P2101: Throttle Actuator Control Position Performance

DTC P2119: Closed Throttle Position Range/Performance

DTC P2176: Throttle Actuator Control Lower Position Not Learned

Diagnostic Fault Information

Circuit	Short to Ground	High Resistance	Open	Short to Voltage	Signal Performance
Motor Control 1	P1516, P2101, P2176	P1516, P2101, P2176	P1516, P2101, P2176	P1516, P2101, P2176	P1516, P2101, P2176
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 centre 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:

Two processors are also used to monitor the TAC system data. Both processors are located within the ECM. Both processors monitor each other's data to verify that the indicated throttle position is correct.

Conditions for Running the DTC

1516 and 2101

P2119

P2176

Conditions for Setting the DTC

P1516

The indicated throttle position does not match the predicted throttle position for more than 0.5 second.

P2101

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

P2119

The ECM determines that the throttle valve did not return to the rest position within 720 milliseconds.

P2176

The difference between the predicted and the actual throttle position is more than a calibrated amount for more than 1.5 seconds.

Action Taken when the DTC Sets

DTCs P1516, P2101, P2119 or P2176 are type A Store Only DTC's.

Conditions for Clearing the MIL/DTC

DTCs P1516, P2101, P2119 or P2176 are type A Store Only DTC's.

Reference Information

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Scan Tool Reference

Control Module References

Circuit/System Verification

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:

•	A throttle blade that is NOT in the rest position.

•	A throttle valve that is binding open or closed.

•	A throttle valve that is free to move open or closed WITHOUT spring pressure.

2. Ignition ON, and the throttle body disconnected, measure for voltage between the motor control 1 and 2 circuits. Voltage should be 0 volts.

⇒	If voltage is more than 0 volts, test the affected motor control circuit for a short to voltage. If the circuit tests normal, replace the ECM.

3. Ignition ON, and the throttle body disconnected, probe the motor control 1 and 2 circuits with a test lamp connected to B+ Test lamp should not illuminate

⇒	If test lamp illuminates, test the affected motor control circuit for a short to ground or open/high resistance.

4. Ignition OFF. Make sure that the ECM completely powers down.
5. Connect a test lamp between TAC motor control 1 circuit and a known ground.
6. The test lamp should illuminate as the ignition is turned ON.

⇒	If the test lamp does not illuminate, test the TAC motor control 1 circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

7. Ignition OFF. Make sure that the ECM completely powers down.
8. Connect a test lamp between TAC motor control 2 circuit and a known ground.
9. The test lamp should illuminate as the ignition is turned ON.

⇒	If the test lamp does not illuminate, test the TAC motor control 2 circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

10. If all circuits test normal, replace the throttle body.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.