The throttle position (TP) sensor is used by the engine control module (ECM) to determine the throttle plate angle for various engine management systems. The TP sensor is a potentiometer type sensor with the following 3 circuits:

The ECM provides the TP sensor with 5 volts on the 5-volt reference circuit, and a ground on the low reference circuit. The TP sensor provides a signal voltage feedback that changes relative to throttle plate angle.

P0122

The ECM detects that the TP sensor voltage is less than 0.3 volts for 2.5 seconds.

P0123

The ECM detects that the TP sensor voltage is greater than 4.9 volts for 2.5 seconds.

DTCs P0122 and P0123 are Type A DTCs.

DTCs P0122 and P0123 are Type A DTCs.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

1. Ignition ON, observe the TP Sensor parameters with a scan tool. Verify the TP sensor voltage is between 0.4-4.5 volts while depressing the accelerator pedal from the rest position to the wide open throttle position (WOT).
2. Rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times. DTC P0122 or P0123 should not set.
3. Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times. DTC P0122 or P0123 should not set.
4. If the vehicle passes the Circuit/System Verification test, then operate the vehicle within the conditions for running the DTC. You may also operate the vehicle within the conditions that are captured in the Freeze Frame/Failure Records Data List.

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

⇒	If greater than the specified range, test the low reference circuit for a short to voltage, or an open/high resistance. If the circuit/connections test 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 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/connections test normal, replace the ECM.

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

4. Verify the scan tool TP sensor voltage parameter is less than 0.3 volt or less than 5 percent.

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

5. Install a 3A fused jumper wire between the signal circuit and the 5-volt reference circuit. Verify the scan tool TP sensor voltage parameter is greater than 4.8 volts or 95 percent.

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

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

1. Ignition OFF, disconnect the harness connector of the TP sensor.
2. Test for 1160-1175 ohms between the 5-volt reference and the low reference terminals of the applicable TP sensor.

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

3. Test the resistance between the signal terminal and the low reference terminal of the TP sensor. Sweep the TP sensor through the entire range. The resistance should vary between 1530 and 630 ohms without any spikes or dropouts.

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

4. Apply 5 volts and ground to the applicable terminals of the TP sensor, and measure the voltage between the signal and the low reference terminals. Sweep the TP sensor through the entire range. The voltage should vary between 4.3-0.6 volts without any spikes or dropouts.

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

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.