For 1990-2009 cars

### 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 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

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Motor Control 1 | 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

### 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 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

#### P1516 and P2101

• | The ignition is ON.

• | The ignition voltage is more than 8 volts.

• | The system is not in the Battery Save mode.

• | The engine is running.

• | DTC P0068 is not set.

• | DTC P1516 and P2101 run continuously when the above conditions are met.

#### P2119

• | The ignition is ON.

• | The ignition voltage is more than 8 volts.

• | The system is in the Battery Save mode.

• | DTC P2119 runs continuously when the above conditions are met.

#### P2176

• | The ignition is ON.

• | The ignition voltage is more than 8 volts.

• | The system is not in the Battery Save mode.

• | The engine is running.

• | DTCs P0068, P0120, P0122, P0123, P0220, P0222, P0223 are not set.

• | DTC P2176 run 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 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 blade 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

• | DTC P1516, P2101, and P2176 are Type A DTCs.

• | DTC P2119 is a Type C DTC.

### Conditions for Clearing the MIL/DTC

• | DTC P1516, P2101, and P2176 are Type A DTCs.

• | DTC P2119 is a Type C DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Description and Operation

Throttle Actuator Control (TAC) System Description

#### Connector End View Reference

• | Engine Controls Connector End Views

• | Engine Control Module Connector End Views

#### 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

### Circuit/System Verification

Ignition ON, engine OFF, 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

Caution: Turn OFF the ignition before inserting fingers into the throttle bore. Unexpected movement of the throttle blade could cause personal injury.

1. Inspect the throttle body for the following conditions:

• | 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

⇒ | 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. Ignition ON, test for 0 volts between the motor control circuit terminal E and ground.

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

4. Ignition ON, test for 0 volts between the motor control circuit terminal F and ground.

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

5. Ignition ON, verify that a test lamp does not illuminate between each motor control circuit terminal E and B+.

⇒ | If test lamp illuminates, test the affected motor control circuit for a short to ground. If the circuit tests normal, replace the ECM.

6. Ignition ON, verify that a test lamp does not illuminate between each motor control circuit terminal F and B+.

⇒ | If test lamp illuminates, test the affected motor control circuit for a short to ground. If the circuit tests normal, replace the ECM.

7. Ignition OFF, allow sufficient time for the ECM to completely power down. Connect a DMM between the motor control 1 circuit terminal F and ground.

Important: When measuring peak voltage, ensure that the DMM is on the proper voltage scale that the response time is set to 1 ms.

8. Measure for B+ on the motor control 1 circuit terminal F as the ignition is turned ON.

⇒ | If the peak voltage is not within 1 volt of B+, test for an open/high resistance. If the circuit tests normal, replace the ECM.

9. Ignition OFF, allow sufficient time for the ECM to completely power down. Connect a DMM between the motor control 2 terminal E circuit and ground.
10. Measure for B+ on the motor control 2 circuit terminal E as the ignition is turned ON.

⇒ | If the peak voltage is not within 1 volt of B+, test for an open/high resistance. If the circuit tests normal, replace the ECM.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Control Module References for ECM replacement, setup, and programming

• | Throttle Body Assembly Replacement