P0120

DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223, P2135, or P2172

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



DTC Descriptors
DTC P0120
- Throttle Position (TP) Sensor 1 Circuit

DTC P0121
- Throttle Position (TP) Sensor 1 Performance

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






Typical Scan Tool Data










Circuit/System Description

The TP sensor used with the throttle actuator control (TAC) system is actually a Hall Effect switch. The Hall Effect switch is surrounded by a magnetic yoke that induces a flux in the magnetic field when the throttle shaft is rotated. The PCM provides a 5-volt reference voltage to the sensor circuits in the TAC module. An integrated circuit (IC) receives and converts the magnetic pulses into two separate TP signal, each with their own characteristics. The TP sensor 1 output provides the powertrain control module (PCM) with a signal voltage that is proportional to the throttle plate movement. Both TP sensor signal voltages are low at closed throttle and increase as the throttle opens. TP sensor 1 determines the actual throttle valve position. TP sensor 2 has a voltage that is more than twice that of TP sensor 1 at idle. TP sensor 2 provides a backup value for TP sensor 1.


Conditions for Running the DTC

* The ignition is ON or the engine is running.
* The DTCs runs continuously when the above condition is met.



Conditions for Setting the DTC


P0120
* The PCM detects that the TP sensor 1 voltage is less than 0.5 volts for greater than 2 seconds.
OR
* The PCM detects that the TP sensor 1 voltage is greater than 4.5 volts for greater than 2 seconds.



P0121
* The difference between the TP sensor 1 and the TP sensor 2 voltage is less than 0.8 volts for greater than 2 seconds.
OR
* The difference between the TP sensor 1 and the TP sensor 2 voltage is greater than 1.6 volts for greater than 2 seconds.


P0122

The PCM detects that the TP sensor 1 voltage is less than 0.2 volts for greater than 2 seconds.

P0123

The PCM detects that the TP sensor 1 voltage is greater than 4.5 volts for greater than 2 seconds.


P0220
* The PCM detects that the TP sensor 2 voltage is less than 0.5 volts for greater than 2 seconds.
OR
* The PCM detects that the TP sensor 2 voltage is greater than 4.8 volts for greater than 2 seconds.


P0222

The PCM detects that the TP sensor 2 voltage is less than 0.5 volts for greater than 2 seconds.

P0223

The PCM detects that the TP sensor 2 voltage is greater than 4.8 volts for greater than 2 seconds.


P2135
* The PCM detects that the difference between TP sensor 1 and TP sensor 2 is less than 0.2 volts for greater than 2 seconds.
* The PCM detects that the TP sensor 1 voltage is less than 0.2 volts for greater than 2 seconds.
* The PCM detects that the TP sensor 2 voltage is less than 0.5 volts for greater than 2 seconds.



Action Taken When the DTC Sets

DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223 and P2135 are Type A DTCs.


Conditions for Clearing the DTC

DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223 and P2135 are Type A DTCs.


Diagnostic Aids

If a shared 5-volt reference circuit is shorted to ground the engine will not start and the PCM will not communicate with the scan tool.


Reference Information
Schematic Reference

Engine Controls Schematics (Electrical Diagrams)
Connector End View Reference

* Powertrain Control Module Connector End Views (Powertrain Control Module Connector End Views)
* Engine Controls Connector End Views (Engine Controls Connector End Views)

Description and Operation

Throttle Actuator Control (TAC) System Description (Throttle Actuator Control (TAC) System Description)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Diagnostic Trouble Code Descriptions)
Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information


Circuit/System Verification

1. Ignition ON, observe that the TP sensor 1 scan tool parameter is between 7-19 percent.
2. Ignition ON, observe that the TP sensor 2 scan tool parameter is between 2.3-2.6 volts.
3. Observe both TP sensor parameters while pressing the accelerator pedal from a closed throttle to WOT. Both TP sensor parameters should change.
4. Rapidly depress the accelerator pedal from the rest position to the WOT position and release pedal. Repeat the procedure several times. DTCs P0120, P0121, P0122, P0123, P0220, P0222, P0223, or P2135 should not set.
5. Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times. DTCs P0120, P0121, P0122, P0123, P0220, P0222, P0223, or P2135 should not set.
6. 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 throttle body assembly.
2. Ignition OFF, test for 5 ohms or less of resistance between the low reference circuit terminal 3 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 tests normal, replace the PCM.

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


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

4. Verify both scan tool TP sensor parameters as listed below:

* TP sensor 1 99 percent
* TP sensor 2 5.0 volts


• If less than the specified range, test the appropriate signal circuit for a short to ground. If the circuit tests normal, replace the PCM.
• If greater than the specified range, test the appropriate signal circuit for a short to voltage. If the circuit tests normal, replace the PCM.


Important: The following test must be performed on both TP sensor signal circuits.


5. Install a 3A fused jumper wire between ground and the TP sensor signal circuit terminal as listed below. Verify the correct scan tool TP sensor parameter as indicated.

* TP sensor 1 signal circuit terminal 6-scan tool parameter 0 percent
* TP sensor 2 signal circuit terminal 4-scan tool parameter 0.2 volts


• If greater than the specified range, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the PCM.

6. If all circuits test normal, test or replace the throttle body assembly.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Throttle Body Assembly Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for PCM replacement, setup, and programming