Without Heavy Duty L96
DTC P0120, P0122, P0123, P0220, P0222, P0223, or P2135 (Without Heavy Duty L96)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions)provides an overview of each diagnostic category.
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
Typical Scan Tool Data
Circuit/System Description
The throttle body assembly contains 2 throttle position (TP) sensors. The TP sensors are mounted to the throttle body assembly and are not serviceable. The TP sensors provide a signal voltage that changes relative to throttle blade angle. The engine control module (ECM) supplies the TP sensors with a common 5 V reference circuit, a common low reference circuit, and two independent signal circuits.
The TP sensors have opposite functionality. TP sensor 1 signal voltage decreases and TP sensor 2 signal voltage increases as the accelerator pedal increases to wide open throttle (WOT).
Conditions for Running the DTC
* DTC P0641 or P0651 is not set.
* The run/crank or powertrain relay voltage is greater than 6 V and reduced power is not active.
* The ignition is ON or the engine is operating.
* DTC P0120, P0122, P0123, P0220, P0222, P0223, P2135 run continuously when the above conditions are met.
Conditions for Setting the DTC
P0120
TP sensor 1 voltage is less than 0.325 V or greater than 4.75 V for greater than 1 s.
P0122
The ECM detects that the TP sensor 1 voltage is less than 0.325 V for greater than 1 s.
P0123
The ECM detects that the TP sensor 1 voltage is greater than 4.75 V for greater than 1 s.
P0220
The TP sensor 2 voltage is less than 0.25 V or greater than 4.59 V for greater than 1 s.
P0222
The ECM detects that the TP sensor 2 voltage is less than 0.25 V for greater than 1 s.
P0223
The ECM detects that the TP sensor 2 voltage is greater than 4.59 V for greater than 1 s.
P2135
The difference between the TP sensor 1 and TP sensor 2 exceeds a predetermined value for greater than 2 s.
Action Taken When the DTC Sets
* DTC P0120, P0122, P0123, P0220, P0222, P0223, and P2135 are Type A DTCs.
* The control module commands the TAC system to operate in the Reduced Engine Power mode.
* A message center or an indicator displays Reduced Engine Power.
* Under certain conditions the control module commands the engine OFF.
Conditions for Clearing the MIL/DTC
DTCs P0120, P0122, P0123, P0220, P0222, P0223, and P2135 are Type A DTCs.
Diagnostic Aids
* If the Throttle Sweep Test is not available on the scan tool, observe the scan tool TP Sensor 1 and 2 Agree/Disagree parameter while performing the following tests:
- Slowly depress the accelerator pedal to WOT and then slowly return the pedal to closed throttle. Repeat the procedure several times.
- Rapidly depress the accelerator pedal from the rest position to the wide open throttle position (WOT) and release pedal. Repeat the procedure several times.
The TP Sensor 1 and 2 Agree/Disagree parameter should display Agree. If Disagree is displayed, continue diagnosis in Circuit/System Testing.
* A high resistance condition on the throttle position and throttle actuator control circuits could cause a DTC to set.
Reference Information
Schematic Reference
Engine Controls Schematics (except L96) ([1][2]Electrical Diagrams)Engine Controls Schematics (L96) ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector End Views By Name)
Description and Operation
Throttle Actuator Control (TAC) System Description (Throttle Actuator Control (TAC) System Description)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions (Powertrain Diagnostic Trouble Code (DTC) Type Definitions)
Scan Tool Reference
Control Module References (Control Module References)for scan tool information
Circuit/System Verification
1. Ignition ON, observe the DTC information with a scan tool. Verify that DTC P0641 or P0651 are not set.
• If a DTC is set, refer to DTC P0641 or P0651 (ECM, Without L96) (P0641) for further diagnosis.
2. Observe the TP sensor 1 and 2 voltage parameters. Both parameters should be between 1.0-4.0 V and change with accelerator pedal input.
Note: If the Throttle Sweep Test is not available on the scan tool, use the accelerator to perform the test. Refer to Diagnostic Aids for further details.
3. Perform the Throttle Sweep Test while observing the TP Sensor 1 and 2 Agree/Disagree parameter with a scan tool. The TP Sensor 1 and 2 Agree/Disagree parameter should display 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 ON, observe the DTC information with a scan tool. Verify that DTC P0120 or P0220 are not the only TP sensor DTCs set.
• If DTC P0120 or P0220 are the only DTCs set, replace the ECM.
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 and all vehicle systems OFF. It may take up to 2 minutes for all vehicle systems to power down. Test for less than 5 ohm between the low reference circuit terminal C 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.
3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal E and ground.
• If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Test for less than 1 V between the TP sensor 1 signal circuit terminal D and ground.
• If greater than specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
5. Install a 3 A fused jumper wire between TP sensor 1 signal circuit terminal D and the 5 V reference circuit terminal E. Verify the scan tool TP sensor 1 voltage parameter is greater than 4.8 V.
• 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. Test for 4.8-5.2 V between the TP sensor 2 signal circuit terminal F and ground.
• If less than specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM.
• If greater than specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the ECM.
7. If all circuits test normal, test or replace the throttle body assembly.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the repair.
* Throttle Body Assembly Replacement (Removal and Replacement)
* Control Module References (Control Module References)for Engine Control Module replacement, programming, and setup