Diagnostic Instructions

DTC Descriptors

DTC P0120: Throttle Position (TP) Sensor 1 Circuit

DTC P0122: Throttle Position (TP) Sensor 1 Circuit Low Voltage

DTC P0123: Throttle Position (TP) Sensor 1 Circuit High Voltage

DTC P0220: Throttle Position (TP) Sensor 2 Circuit

DTC P0222: Throttle Position (TP) Sensor 2 Circuit Low Voltage

DTC P0223: Throttle Position (TP) Sensor 2 Circuit High Voltage

DTC P2135: Throttle Position (TP) Sensor 1-2 Correlation

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
TP Sensor 1 Signal	P0122	P0122, P2135,	P0123	P0068, P0121
TP Sensor 1 and 2 5-Volt Reference	P0651	P0122, P0222, P2135	P0651, P2135	--
TP Sensor 1 and 2 Low Reference	--	P0123, P0223, P2135	--	--
TP Sensor 2 Signal	P0222	P0223, P2135	P0223	P0068, P0121

Typical Scan Tool Data

TP Sensor 1

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running at various operating conditions Parameter Normal Range: 4.75-0.35 V
TP Sensor 1 Signal	0 V	0 V	5 V
TP Sensor 5-Volt Reference	0 V	0 V	5 V
TP Sensor Low Reference	--	5 V	--

TP Sensor 2

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Engine running at various operating conditions Parameter Normal Range: 0.25-4.59 V
TP Sensor 2 Signal	0 V	5 V	5 V
TP Sensor 5-Volt Reference	0 V	0 V	5 V
TP Sensor Low Reference	--	5 V	--

Circuit/System Description

The throttle actuator control (TAC) system uses two throttle position (TP) sensors to monitor the throttle position. The TP sensors 1 and 2 are located within the throttle body assembly. Each sensor has a 5-volt reference circuit, a low reference circuit, and a signal circuit.

Two processors are also used to monitor the TAC system data. Both processors are located within the engine control module (ECM). Each signal circuit provides both processors with a signal voltage proportional to throttle plate movement. Both processors monitor each other's data to verify that the indicated TP calculation is correct.

Conditions for Running the DTC

P0120, P0122, P0123, P0220, P0222, and P0223

P2135

Conditions for Setting the DTC

P0120

TP sensor 1 voltage is less than 0.325 volt or greater than 4.75 volts for greater than 1 second.

P0122

The ECM detects that the TP sensor 1 voltage is less than 0.325 volt for greater than 1 second.

P0123

The ECM detects that the TP sensor 1 voltage is greater than 4.75 volts for greater than 1 second.

P0220

The TP sensor 2 voltage is less than 0.25 volt or greater than 4.59 volts for greater than 1 second.

P0222

The ECM detects that the TP sensor 2 voltage is less than 0.25 volt for greater than 1 second.

P0223

The ECM detects that the TP sensor 2 voltage is greater than 4.59 volts for greater than 1 second.

P2135

The difference between the TP sensor 1 and TP sensor 2 exceeds a predetermined value for greater than 2 seconds.

Action Taken When the DTC Sets

Conditions for Clearing the MIL/DTC

DTCs P0120, P0122, P0123, P0220, P0222, P0223, and P2135 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

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Verify that the following DTCs are not set: DTC P0641 or P0651.

⇒	If any of the DTCs are set, refer to DTC P0641 or P0651.

2. Ignition ON, observe the scan tool TP sensor 1 voltage parameter. The reading should be between 4.75-0.35 volts and change with accelerator pedal input.
3. Ignition ON, observe the scan tool TP sensor 2 voltage parameter. The reading should be between 0.25-4.59 volts and change with accelerator pedal input.
4. Ignition ON, observe the scan tool TP sensor 1 and 2 parameter. The scan tool should indicate agree.
5. Clear the DTCs with the scan tool.
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. Verify the following DTCs are not set: DTC P0120 or P0220.

⇒	If either or both DTCs P0120 or P0220 are set, and are the only DTCs set, replace the ECM.

8. 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

Note: All modules must be powered down or misdiagnosis may result.

1. Ignition OFF, disconnect the scan tool and wait 60 seconds to ensure all modules are powered down.
2. Ignition OFF, disconnect the harness connector at the throttle body.
3. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal C and ground.

⇒	If greater than 5 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the ECM.

4. Ignition ON, test for 4.8-5.2 volts between 5-volt reference circuit terminal E and ground.

⇒	If less than 4.8 volts, test 5-volt reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

⇒	If greater than 5.2 volts, test the 5-volt reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.

5. Verify the scan tool TP sensor 1 voltage is less than 0.1 volt.

⇒	If greater than 0.1 volt, test the signal circuit terminal D for a short to voltage. If the circuit tests normal, replace the ECM.

6. Verify the scan tool TP sensor 2 voltage is greater than 4.8 volts.

⇒	If less than 4.8 volts, test the signal circuit for a short to ground. If the circuit tests normal, replace the ECM.

7. Install a 3A fused jumper wire between the signal circuit terminal D and the 5-volt reference circuit terminal E of the TP sensor 1. Verify the TP sensor 1 voltage is greater than 4.8 volts.

⇒	If less than 4.8 volts, test the TP sensor 1 signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

8. Install a 3A fused jumper wire between the signal circuit terminal F and the low reference circuit terminal C of the TP sensor 2. Verify that the TP sensor 2 voltage is less than 0.1 volt.

⇒	If greater than 0.1 volt, test the TP sensor 2 signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM.

9. Ignition OFF for 90 seconds, disconnect the harness connector at the ECM.
10. Test for less than 5 ohms of resistance on all TP sensor circuits between the following terminals:

•	ECM X2 signal circuit terminal 57 and the throttle body connector terminal D

•	ECM X2 signal circuit terminal 59 and the throttle body connector terminal F

•	ECM X2 5-volt reference circuit terminal 53 and the throttle body connector terminal E

⇒	If greater than 5 ohms, repair the affected circuit for open/high resistance.

11. Test for infinite resistance between TP sensor 1 signal circuit terminal D and TP sensor 2 signal circuit terminal F.

⇒	If less than infinite resistance, repair the short between TP sensor 1 signal circuit and TP sensor 2 signal circuit.

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.