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	High Resistance	Open	Short to Voltage	Signal Performance
TP Sensor 1 Signal	P0122	P2135	P0122, P2135	P0123	P0068, P0120, P0121
TP Sensor 2 Signal	P0222	P2135	P0223, P2125	P0223	P0068, P0121, P0220
TP Sensor 1 and 2 5-Volt Reference	P0651	P2135	P0122, P0222	P0651	--
TP Sensor 1 and 2 Low Reference	--	P2135	P0123, P0223	--	--

Typical Scan Tool Data

TP Sensor 1

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The ignition is ON, with the engine OFF. Normal TP 1 Parameter: 4.20-0.5 V
TP Sensor 1 and 2 5-Volt Reference	0.04 V	0.00 V	4.98 V
TP Sensor 1 Signal	0.00 V	0.00 V	4.98 V
TP Sensor 1 and 2 Low Reference	--	4.98 V	--

TP Sensor 2

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: The ignition is ON, with the engine OFF. Normal TP 2 Parameter: 0.7-4.5 V
TP Sensor 1 and 2 5-Volt Reference	0.04 V	0 V	3.63 V
TP Sensor 2 Signal	0.00 V	4.98 V	4.98 V
TP Sensor 1 and 2 Low Reference	--	4.98 V	--

Circuit/System Description

The throttle actuator control (TAC) system uses 2 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 signal circuit and share a 5-volt reference and low reference 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

Conditions for Setting the DTC

P0120

TP sensor 1 voltage is less than 0.35 volt or more than 4.58 volts for less than 1 second.

P0122

The ECM detects that the TP sensor 1 voltage is less than 0.35 volt for less than 1 second.

P0123

The ECM detects that the TP sensor 1 voltage is more than 4.58 volts for less than 1 second.

P0220

The TP sensor 2 voltage is less than 0.35 volt or more than 4.58 volts for less than 1 second.

P0222

The ECM detects that the TP sensor 2 voltage is less than 0.35 volt for less than 1 second.

P0223

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

P2135

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

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

Description and Operation

Throttle Actuator Control (TAC) System Description

Electrical Information Reference

DTC Type Definitions

Scan Tool Reference

Circuit/System Verification

1. Ignition ON, observe the TP sensor 1 for a voltage parameter between 0.35-4.58 volts, with the accelerator pedal in the released position.
2. Ignition ON, observe the TP sensor 2 for a voltage parameter between 0.35-4.597 volts, with the accelerator pedal in the released position with a scan tool.
3. With a scan tool, observe the TP sensors 1 and 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. Ignition OFF for 60 seconds, operate the vehicle within the Conditions for Running the DTCs.
6. Ignition ON, perform several accelerator pedal sweeps, then observe the previous TP sensor parameters and DTC information with the scan tool.

⇒	If DTC P0120 or P0220 is the only DTC set, and all of the previous TP sensor parameters are normal, replace the ECM.

7. Verify that DTCs P0641 or P0651 are not set.

⇒	If DTC P0641 or P0651 is set, refer to DTC P0641 or P0651 .

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the throttle body. Allow sufficient time for the ECM to completely power down. This can be verified by a no communication message on the scan tool.
2. Ignition OFF, test for less than 5 ohms of resistance between the low reference circuit terminal 3 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.

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

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

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

4. 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 1 for a short to voltage. If the circuit tests normal, replace the ECM.

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

⇒	If less than 4.8 volts, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the ECM.

6. Install a 3A fused jumper wire between the signal circuit terminal 1 and the 5-volt reference circuit terminal 5 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 short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.

7. Ignition ON, verify that a test lamp does not illuminate between the TP sensor 2 signal circuit terminal 2 and ground.

⇒	If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.

8. Install a 3A fused jumper wire between the signal circuit terminal 2 and the low reference circuit terminal 3 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 an open/high resistance. If the circuit tests normal, replace the ECM.

9. Ignition OFF, 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 C2 signal circuit terminal 64 to TP terminal 1

•	ECM C2 signal circuit terminal 66 to TP terminal 2

•	ECM C2 5-volt reference circuit terminal 44 to TP terminal 5

⇒	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 1 and TP sensor 2 signal circuit terminal 2.

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

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

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.