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, P2119, P2176 | P1516, P2101, P2119, P2176 | P1516, P2101, P2119, P2176 | P1516, P2101, P2119, P2176
Motor Control 2 | P1516, P2101, P2119, P2176 | P1516, P2101, P2119, P2176 | P1516, P2101, P2119, P2176 | P1516, P2101, P2119, 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 others data, verify that the indicated throttle position is correct.

### Conditions for Running the DTC

#### P1516

• | The ignition is in Run or Crank.

• | When engine speed is more than 0, system voltage is more than 5.4 volts or the engine speed is equal to 0, The system is not in Battery Saver mode and system voltage is more than 11 volts.

• | DTC P0068 or P0121 are not set.

• | Not set the ignition modification DTC.

• | DTC P1516 runs continuously when the above conditions are met.

#### P2101

• | The ignition is in Run or Crank.

• | When engine speed is more than 0, system voltage is more than 5.5 volts or the engine speed is equal to 0, The system is not in Battery Saver mode and system voltage is more than 11 volts.

• | DTC P0068 or P0121 are not set.

• | Not set the ignition modification DTC.

• | DTC P1516 runs continuously when the above conditions are met.

#### P2119

• | Ignition ON.

• | Ignition voltage is greater than 8 volts.

• | The system is in the Battery Saver mode.

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

#### P2176

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

• | The MIN Throttle learn is in active status.

• | The Steady throttle Position lasts 40 ms.

• | The ignition is in Run or Ignition.

• | Not set the ignition modification DTC

• | 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 0.18 second.

#### P2101

• | The Engine Control Module (ECM) detects that the difference between the measured throttle position and calculated position is more than a predetermined value.

• | The condition occurs during 15 times continuous tests.

#### P2119

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

#### P2176

When the Learned Minimum TP of master procedures, the throttle pressure Sensor is more than a calibrated value for more than 1.8 seconds.

### Action Taken When the DTC Sets

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

• | DTC P2119 is a Type C DTC.

• | The control module commands the TAC system to operate in the Reduced Engine Power mode.

• | The message center or the indicator displays Reduced Engine Power.

• | Under certain conditions the control module commands the engine OFF.

### Conditions for Clearing the DTC

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

• | DTC P2119 is a Type C DTC.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

• | Engine Controls Connector End Views

• | Engine Control Module Replacement

#### 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

Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

• | Scan Tool Data List

• | Scan Tool Data Definitions

### Circuit/System Verification

With engine OFF, turn the ignition ON, observe the Throttle Position (TP) sensor 1 indicated position with a scan tool. The throttle position should increase as pedal is applied and decrease as the 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:

• | Throttle valve 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 positions WITHOUT spring pressure

⇒ | If a condition is found, replace the throttle body assembly.

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 motor control 1 circuit terminal B and ground.

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

4. Ignition ON, test for 0 volts between Motor Control 2 circuit terminal A and ground.

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

5. Ignition ON, verify that the test lamp illuminates between motor control 1 circuit terminal B and battery positive.

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

6. Ignition ON, verify that the test lamp illuminates between motor control the 2 circuit terminal A and battery positive.

⇒ | If the test lamp illuminates, test the motor control circuit for a short to ground. If the circuit test 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 B and ground.

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

8. With the ignition ON, measure voltage of motor control 1 terminal B is B+.

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

9. Ignition OFF, allow sufficient time for the ECM to completely power down.
10. With the ignition ON, measure voltage of motor control 2 terminal A is B+.
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