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 P0122 00: Throttle Position Sensor 1 Circuit Low Voltage
DTC P0123 00: Throttle Position Sensor 1 Circuit High Voltage
DTC P0222 00: Throttle Position Sensor 2 Circuit Low Voltage
DTC P0223 00: Throttle Position Sensor 2 Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Throttle Position Sensor 1 signal | P0122 00 | P0122 00 | P0123 00 | P0121 00
Throttle Position Sensor 1 5 V Reference | P0122 00 | P0122 00 | P0123 00 | --
Throttle Position Sensor 1 Low Reference | -- | P0123 00 | -- | --
Throttle Position Sensor 2 Signal | P0222 00 | P0222 00 | P0123 00 | P0121 00
Throttle Position Sensor 2 5 V Reference | P0222 00 | P0222 00 | P0223 00 | --
Throttle Position Sensor 2 Low Reference | -- | P0223 00 | -- | --

### Typical Scan Tool Data

#### Throttle Position Sensor 1

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Parameter Normal Range: 0.2-4.82 V
Throttle Position Sensor 1 Signal | 0 V | 5 V | 5 V
Throttle Position Sensor 1 5 V Reference | 0 V | 0 V | 5 V
Throttle Position Sensor 1 Low Reference | -- | 5 V | --

#### Throttle Position Sensor 2

Circuit | Short to Ground | Open | Short to Voltage
--- | --- | --- | ---
Parameter Normal Range: 4.82-0.19 V
Throttle Position Sensor 2 Signal | 0 V | 0 V | 5 V
Throttle Position Sensor 2 5 V Reference | 0 V | 0 V | 5 V
Throttle Position Sensor 2 Low Reference | -- | 5 V | --

### Circuit/System Description

The throttle actuator control (TAC) system uses 2 throttle position sensors to monitor the throttle position. The throttle position sensors 1 and 2 are located within the throttle body assembly. Each sensor has the following circuits:

• | A 5 V reference circuit

• | A low reference circuit

• | A signal circuit

### Conditions for Running the DTC

• | The engine is running.

• | DTCs P0642 00, P0643 00 are not set.

### Conditions for Setting the DTC

#### P0123 00 or P0223 00

The reference voltage is greater than 4.8 V.

#### P0122 00 or P0222 00

The reference voltage is less than 0.2 V.

### Action Taken When the DTC Sets

• | DTCs P0122 00, P0123 00, P0222 00, P0223 00 are Type A DTCs

• | The control module commands the TAC system to operate in the reduced engine power mode.

• | A message center or an indicator displays reduced engine power.

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

### Conditions for Clearing the DTC

DTCs P0122 00, P0123 00, P0222 00, P0223 00 are Type A DTCs

### 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, observe the Throttle Position Sensor 1 parameter. The reading should be between 0.2-4.8 V and change with accelerator pedal input.
2. Ignition ON, observe the Throttle Position Sensor 2 parameter. The reading should be between 0.2-4.8 V and change with accelerator pedal input.
3. Observe the Throttle Position Sensor 1 and Throttle Position Sensor 2 parameter. The scan tool should indicate Agree.
4. Clear the DTCs with the scan tool. Operate the vehicle within the Conditions for Running the DTC, or within the conditions that you observed from the Freeze Frame/Failure Records.
5. Verify that DTCs P0642 00, P0643 00, P0652 00 or P0653 00 are not set.

⇒ | If DTCs P0642 00, P0643 00, P0652 00 or P0653 00 are set, refer to LINK DTC P0642, P0643, P0652 or P0653

6. 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.
7. Inspect the throttle body for the following conditions:

### Circuit/System Testing

Note: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF, disconnect the harness connector at the B107 Accelerator Pedal Position (APP) Sensor. Allow sufficient time for the K20 Engine Control Module (ECM) to completely power down.
2. Ignition OFF, test for less than 5 Ω between the low reference circuit terminal 6 and ground.

⇒ | If greater than 5 Ω, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal 2 and ground.

⇒ | If less than 4.8 V, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

⇒ | If greater than 5.2 V, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

4. Verify the scan tool Throttle Position Sensor 1 voltage is greater than 4.8 V.

⇒ | If less than 4.8 V, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

5. Verify the scan tool Throttle Position Sensor 2 voltage is less than 0.1 V.

⇒ | If greater than 0.1 V, test the signal circuit terminal 4 for a short to voltage. If the circuit tests normal, replace the K20 Engine Control Module (ECM).

6. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the low reference circuit terminal 6 of the Throttle Position Sensor 1. Verify that the Throttle Position Sensor 1 voltage is less than 0.1 V.

⇒ | If greater than 0.1 V, test the Throttle Position Sensor 1 signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

7. Install a 3 A fused jumper wire between the signal circuit terminal 4 and the 5 V reference circuit terminal 2 of the Throttle Position Sensor 2. Verify the Throttle Position Sensor 2 voltage is greater than 4.8 V.

⇒ | If less than 4.8 V, test the Throttle Position Sensor 2 signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

8. Ignition OFF, disconnect the harness connector at the ECM.
9. Test for less than 5 Ω on all throttle position sensor circuits between the following terminals:

• | The 5 V reference circuit terminal 2 to the corresponding ECM terminal

• | The signal circuit terminal 1 to the corresponding ECM terminal

• | The signal circuit terminal 4 to the corresponding ECM terminal

⇒ | If greater than 5 Ω, repair the affected circuit.

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

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Throttle Body Assembly Replacement

• | Engine Control Module Replacement for ECM replacement, setup, and programming