P0123
DTC P0120-P0123, P0220, P0222, P0223, or P2135 (Without Supercharger)
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 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 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
P0120, P0122, P0123, P0220, P0222, and P0223
* 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 run continuously when the above conditions are met.
P0121
* DTCs P0102, P0103, P0107, P0108, P0111, P0112, P0113, P0116, P0117, P0118, P0128, P0315, P0335, P0336, or P3400 is not set.
* The engine speed is between 450-6,700 RPM.
* The engine coolant temperature (ECT) is between -7 to +125°C (19-257°F).
* The intake air temperature (IAT) is between -20 to +125°C (-4 to +257°F).
* DTC P0121 runs continuously when the above conditions are met.
P2135
* DTC P0120, P0122, P0123, P0220, P0222, P0223, 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 P2135 runs continuously when the above conditions are met.
Conditions for Setting the DTC
P0121
The ECM detects the TP sensor is stuck within range for greater than 1 s.
P0120
The ECM detects the 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 the TP sensor 1 voltage is less than 0.325 V for greater than 1 s.
P0123
The ECM detects the TP sensor 1 voltage is greater than 4.75 V for greater than 1 s.
P0220
The ECM detects 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 the TP sensor 2 voltage is greater than 4.59 V for greater than 1 s.
P2135
The ECM detects the difference between the TP sensor 1 and TP sensor 2 exceeds a predetermined value for greater than 1 s.
Action Taken When the DTC Sets
* DTC P0120, P0122, P0123, P0220, P0222, P0223, and P2135 are Type A DTCs.
* DTC P0121 is a Type B DTC.
* The ECM 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.
DTC P0121 is a Type B DTC.
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 (LS3) [1][2]Electrical DiagramsEngine Controls Schematics (LS9) [1][2]Electrical DiagramsEngine Controls Schematics (LS7) [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Folding Top 5 Bow Lowered Switch (CM7)
Description and Operation
Throttle Actuator Control (TAC) System Description Description and Operation
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. If you were sent here from DTC P0068, P0101, P0106, P012B, or P1101 refer to Circuit/System Testing.
2. Ignition ON.
3. Verify that DTC P0641 or P0651 is not set.
• If any of the DTCs are set
Refer to DTC P0641 or P0651 (ECM With Supercharger) Powertrain Management (ECM)DTC P0641 or P0651 (ECM Without Supercharger) Powertrain Management (ECM) for further diagnosis.
• If none of the DTCs are set
4. Verify the scan tool TB Idle Airflow Compensation parameter is less than 90 %.
• 90 % or greater
Refer to Throttle Body Cleaning Procedures.
• If less than 90 %
5. Verify the scan tool TP Sensor 1 and TP Sensor 2 voltage parameters are between 1.0-4.0 V and change with accelerator pedal input.
• If not between 1.0-4.0 V or does not change
Refer to Circuit/System Testing
• If between 1.0-4.0 V and changes
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.
6. Verify the scan tool TP Sensors 1 and 2 Agree/Disagree parameter displays Agree while performing the Throttle Sweep Test with a scan tool.
• If Disagree
Refer to Circuit/System Testing
• If Agree
7. 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.
8. Ignition ON.
9. 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 engine control module
• If DTC P0120 or P0220 are not set
10. Verify DTC P0120, P0121, P0122, P0123, P0220, P0222, P0223, and P2135 is not set.
• If any of the DTCs are set
Refer to Circuit/System Testing
• If none of the DTCs are set
11. Determine the current vehicle testing altitude.
12. Verify the scan tool MAP Sensor pressure parameter is within range specified in the Altitude Versus Barometric Pressure Altitude Versus Barometric Pressure table.
• The MAP Sensor pressure is not in range
Refer to DTC P0106 (Without Supercharger) P0106DTC P0106 (Supercharger) P0106.
• The MAP Sensor pressure is within range
13. Engine idling.
14. Verify the scan tool MAP Sensor pressure parameter is between 26-52 kPa (3.8-7.5 psi) and changes with accelerator pedal input.
• If not between 26-52 kPa (3.8-7.5 psi) or does not change
Refer to DTC P0106 (Without Supercharger) P0106DTC P0106 (Supercharger) P0106.
• If between 26-52 kPa (3.8-7.5 psi) and changes
15. Verify the scan tool MAF Sensor g/s parameter changes smoothly and gradually as the engine speed is increased and decreased while performing the actions listed below.
1. Engine idling
2. Perform the scan tool snapshot function.
3. Increase the engine speed slowly to 3,000 RPM and then back to idle.
4. Exit from the scan tool snapshot and review the data.
5. Observe the MAF Sensor parameter frame by frame with a scan tool.
• The MAF Sensor parameter does not change smoothly and gradually
Refer to DTC P0101 (Without Supercharger) P0101DTC P0101 (Supercharger) P0101
• The MAF Sensor parameter changes smoothly and gradually
16. 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.
17. Verify a DTC does not set.
• If any DTC sets
Refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle for further diagnosis.
• If no DTCs set
18. All OK
Circuit/System Testing
Note:
Disconnecting the throttle body harness connector causes additional DTCs to set.
1. Ignition OFF, and all vehicle systems OFF, disconnect the harness connector at Q38 throttle body assembly. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 5 ohms between the low reference circuit terminal C and ground.
• If 5 ohms or greater
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for less than 2 ohms in the low reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If less than 5 ohms
3. Ignition ON.
4. Test for 4.8-5.2 V between the 5 V reference circuit terminal E and ground.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for infinite resistance between the 5 V reference circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the 5 V reference circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
2. Test for less than 1 V between the 5 V reference circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 engine control module.
• If between 4.8-5.2 V
5. Ignition ON.
6. Test for less than 1 V between the TP sensor 1 signal circuit terminal D and ground.
• If 1.0 V or greater
1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 engine control module.
• If 1.0 V or less
7. Install a 3 A fused jumper wire between TP sensor 1 signal circuit terminal D and the 5 V reference circuit terminal E.
8. Verify the scan tool TP sensor 1 voltage parameter is greater than 4.8 V.
• If 4.8 V or less
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If 4.8 or greater
9. Test for 4.8-5.2 V between the TP sensor 2 signal circuit terminal F and ground.
• If less than 4.8 V
1. Ignition OFF, disconnect the harness connector at the K20 engine control module.
2. Test for infinite resistance between the signal circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the K20 engine control module.
• If greater than 5.2 V
1. Ignition OFF, disconnect the harness connector at the K20 engine control module, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the K20 engine control module.
• If between 4.8-5.2 V
10. Test or replace the Q38 throttle body assembly.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Throttle Body Assembly Replacement (Without LS9) Removal and ReplacementThrottle Body Assembly Replacement (LS9) Removal and Replacement
* Control Module References Control Module References for engine control module replacement, programming, and setup