DTC P0122 or P0123. Chevrolet Joy 2008

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 P0122: Throttle Position (TP) Sensor Circuit Low Voltage
DTC P0123: Throttle Position (TP) Sensor Circuit High Voltage

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
5-Volt Reference | P0122 | P0122 | P0123 | --
TP Sensor Signal | P0122 | P0122 | P0123 | --
Low Reference | -- | P0123 | -- | --

### Circuit/System Description

The throttle body assembly contains a throttle position (TP) sensor. The TP sensor is mounted externally on the throttle body assembly. The TP sensor is a potentiometer which provides a signal voltage that changes relative to the throttle blade angle. The engine control module (ECM) supplies the TP sensor with a 5-volt reference circuit, a low reference circuit, and a signal circuit. The TP sensor signal voltage decreases from less than 1 volt at idle to more than 4 volts at wide open throttle (WOT).

### Conditions for Running the DTC

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

• | The DTCs run continuously when the above condition is met.

### Conditions for Setting the DTC

#### P0122

The ECM detects that the TP sensor voltage is less than 0.1 volt.

#### P0123

The ECM detects that the TP sensor voltage is more than 4.8 volts.

### Action Taken When the DTC Sets

DTC P0122 and P0123 are Type A DTCs.

### Conditions for Clearing the DTC

DTC P0122 and P0123 are Type A DTCs.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### 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, slowly depress the accelerator pedal from the rest position to wide open throttle and observe the scan tool TP Sensor voltage parameter. The voltage should change.
2. Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the TP sensor.
2. Ignition OFF for 30 seconds, test for less than 5 ohms of resistance between the low reference circuit terminal B and ground.

⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal A and ground.

⇒ | If less than the specified range, test the 5-volt reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the ECM.

⇒ | If greater than the specified range, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

4. Verify the scan tool TP Sensor voltage parameter is less than 0.3 volt.

⇒ | If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

5. Install a 3A fused jumper wire between the signal circuit terminal C and the 5-volt reference circuit terminal A. Verify the scan tool TP sensor voltage parameter is greater than 4.8 volts.

⇒ | If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

6. If all circuits test normal, test or replace the TP sensor.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

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