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).

Important: The scan tool displays a voltage near 0.0 volt. Do not use the scan tool voltage parameter to determine if there is a TP sensor condition.

P0122

The ECM detects that the TP sensor voltage is less than 0.14 volt for more than 5 seconds.

P0123

The ECM detects that the TP sensor voltage is more than 4.9 volts for more than 5 seconds.

DTC P0122 and P0123 are Type A DTCs.

DTC P0122 and P0123 are Type A DTCs.

Schematic Reference

Engine Controls Schematics

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Engine running, observe the scan tool TP Sensor voltage parameter. The reading should be between 0.4-4.5 volts.
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.

1. Ignition OFF, disconnect the harness connector at the TP sensor.
2. Ignition OFF, 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.

Important: The 5-volt reference circuits are internally and externally connected at the ECM. Other component DTCs may be set. If other DTCs are set, review the electrical schematic and diagnose the applicable circuits and components.

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.

1. Ignition OFF, disconnect the harness connector at the TP sensor.
2. Test for 5150-5350 ohms of resistance between the 5-volt reference terminal A and the low reference terminal B.

⇒	If not within the specified range, replace the TP sensor.

3. Sweep the TP sensor through the entire range while monitoring the resistance between the signal terminal C and the low reference terminal B. The resistance should vary between 2,500-6,800 ohms without any spikes or dropouts.

⇒	If not within the specified range or is erratic, replace the TP sensor.

4. Sweep the TP sensor through the entire range while applying 5 volts and ground to the applicable terminals. Test the voltage between the signal terminal C and the low reference terminal B. The voltage should vary between 0.6-4.7 volts without any spikes or dropouts.

⇒	If not within the specified range or is erratic, replace the TP sensor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.