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 Descriptor

DTC P1516 00: Throttle Actuator Control (TAC) Motor Control Circuit
DTC P2101 00: Control Module Throttle Actuator Position Performance
DTC P2119 00: Throttle Closed Position Performance
DTC P2176 00: Minimum Throttle Position Not Learned

### Diagnostic Fault Information

Circuit | Short to Ground | Open High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Motor Control 1 | P1516 00, P2101 00, P2176 00 | P1516 00, P2101 00, P2176 00 | P1516 00, P2101 00, P2176 00 | P1516 00, P2101 00, P2176 00
Motor Control 2 | P1516 00, P2101 00, P2176 00 | P1516 00, P2101 00, P2176 00 | P1516 00, P2101 00, P2176 00 | P1516 00, P2101 00, P2176 00

### Circuit/System Description

The engine control module (ECM) is the control center for the throttle body 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 throttle body (TAC) motor. The throttle body (TAC) motor system uses the following circuits:

• | Throttle body (TAC) motor control 1

• | Throttle body (TAC) motor control 2

Two processors are also used to monitor the throttle body (TAC) motor system data. Both processors are located within the ECM. Both processors monitor each others data to verify that the indicated throttle position is correct.

### Conditions for Running the DTC

#### P1516 00 or P2101 00

• | The ignition is ON or the engine is operating.

• | The ignition voltage is greater than 7 V.

• | The system is not in battery safe mode.

• | DTC P0068 00 is not set.

• | DTCs P1516 00 and P210 001 run continuously once the above conditions are met for greater than 5 s.

#### 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 6 V.

• | DTC P2119 00 runs when the ignition is turned to the OFF position, when the above conditions are met.

#### P2176 00

• | The ignition is ON.

• | The ignition voltage is greater than 6 V.

• | The system is not in battery safe mode

• | The engine is running.

• | DTCs P0068 00, P0120 00, P0122 00, P0123 00, P0220 00, P0222 00, P0223 00 are not set.

• | DTC P2176 00 run continuously when the above conditions are met.

### Conditions for Setting the DTC

#### P1516 00

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

#### P2101 00

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

#### P2119 00

The ECM determines that the throttle blade did not return to the rest position within 720 ms.

#### P2176 00

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

### Action Taken When the DTC Sets

• | DTCs P1516 00, P2101 00, and P2176 00 are Type B DTCs.

• | DTC P2119 00 is a Type C DTC.

### Conditions for Clearing the DTC

• | DTCs P1516 00, P2101 00, and P2176 00 are Type B DTCs.

• | DTC P2119 00 is a Type C DTC.

### Diagnostic Aids

• | A high resistance condition with the throttle position sensor circuits may cause DTCs P151 006, 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

#### 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. Ignition ON, engine OFF, use a scan tool to observe the throttle position 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.

Note: A low voltage condition may set this DTC.

2. Review the freeze frame/failure records and ensure sufficient ignition voltage was present when the DTC was set.

⇒ | If voltage was low, verify with the owner that the battery was not discharged. If the battery has not been discharged, refer to Power Mode Mismatch

3. Operate the vehicle within the conditions for running the DTC. 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 a 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 of the Q38 Throttle Body.
3. Ignition ON, test for greater than 9 V on the Q38 Throttle Body motor control circuit X1 pin A or Q38 Throttle Body motor control circuit terminal B (X1).

⇒ | If less than the specified range, test the Q38 Throttle Body motor control circuit X1 pin A or Q38 Throttle Body motor control circuit terminal B (X1) circuits for a short to ground, or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Ignition ON, probe the Q38 Throttle Body motor control circuit terminal A (X1) or Q38 Throttle Body motor control circuit terminal B (X1) with a test lamp connected to ground. Verify the test lamp does not illuminate.

⇒ | If the test lamp illuminates, test the Q38 Throttle Body motor control circuit terminal A (X1) or Q38 Throttle Body motor control circuit terminal B (X1) for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. Set the DMM to AC hz on the 400 mV scale. Engine idling, test for greater than 2000 AC hz between Q38 Throttle Body motor control circuit terminal A (X1) or Q38 Throttle Body motor control circuit terminal B (X1) and ground while commanding the engine speed to 1950 RPM with a scan tool.

⇒ | If less than the specified value, replace the K20 Engine Control Module (ECM).

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Throttle Body Assembly Replacement

• | Control Module References for engine control module replacement, setup, and programming