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DTC P0121-P0123, P0222, P0223, or P2135 - LF1, LFW

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    • Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0121: Throttle Position Sensor Performance

DTC P0122: Throttle Position Sensor 1 Circuit Low Voltage

DTC P0123: Throttle Position Sensor 1 Circuit High Voltage

DTC P0222: Throttle Position Sensor 2 Circuit Low Voltage

DTC P0223: Throttle Position Sensor 2 Circuit High Voltage

DTC P2135: Throttle Position Sensors 1-2 Not Plausible

Diagnostic Fault Information

Circuit

Short to Ground

High Resistance

Open

Short to Voltage

Signal Performance

5 V Reference

P06A3

-

P0122, P0222,

P06A3

P0121

TP Sensor 1 Signal

P0122

P2119, P2135, P2176

P0122

P0123, P2135

P0121, P2135

TP Sensor 2 Signal

P0222

P2135

P0223

P0223, P2135

P0121, P2135

Low Reference

-

-

P0123, P0223

-

-

Typical Scan Tool Data

TP Sensor 1

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: The engine is idling.

Parameter Normal Range: TP Sensor 1 3.0-4.0 V

5 V Reference

0.00 V

0.00 V

4-5 V

TP Sensor 1 Signal

0.00 V

0.00 V

5.00 V

Low Reference

-

4-5 V

-

TP Sensor 2

Circuit

Short to Ground

Open

Short to Voltage

Operating Conditions: The engine is idling.

Parameter Normal Range: TP Sensor 2 1.4-2.4 V

5 V Reference

0-0.5 V

0-0.5 V

3-5 V

TP Sensor 2 Signal

0.00 V

5.00 V

5.00 V

Low Reference

-

5.00 V

-

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 2 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

P0121

    • DTCs P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0335, or P0336 is not set.
    • The engine speed is between 400-7,000 RPM.
    • The engine coolant temperature (ECT) is between 69-127°C (156-260°F).
    • The inlet air temperature (IAT) is between -20 to +125°C (-4 to +257°F).
    • The DTC runs continuously when the above conditions are met.

P0122, P0123, P0222, P0223

    • DTC P06A3 is not set.
    • The ignition is ON or the engine is running.
    • The engine is not operating in reduced power mode.
    • The ignition voltage is greater than 6 V.
    • The DTCs runs continuously when the above conditions are met.

P2135

    • DTCs  P0121, P0122, P0123, P0222, P0223, or P06A3 are not set.
    • The ignition is ON or the engine is running.
    • The engine is not operating in reduced power mode.
    • The ignition voltage is greater than 6 V.
    • The DTCs runs continuously when the above conditions are met.

Conditions for Setting the DTC

P0121

The ECM detects that the TP sensor 1 voltage is stuck in range for less than 1 s.

P0122

The ECM detects that the TP sensor 1 voltage is less than 0.3 V for less than 1 s.

P0123

The ECM detects that the TP sensor 1 voltage is greater than 4.8 V for less than 1 s.

P0222

The ECM detects that the TP sensor 2 voltage is less than 0.3 V for less than 1 s.

P0223

The ECM detects that the TP sensor 2 voltage is greater than 4.6 V for less than 1 s.

P2135

The ECM detects that TP sensor 1 and TP sensor 2 disagree greater than 7-10 percent for less than 1 s.

Action Taken When the DTC Sets

P0121

    • DTC P0121 is a type B DTC
    • The ECM commands the throttle actuator control (TAC) system to operate in a Reduced Engine Power mode.

P0122, P0123, P0222, P0223, or P2135

    • DTC P0122, P0123, P0222, P0223, and P2135 are type A DTCs
    • The ECM commands the throttle actuator control (TAC) system to operate in a Reduced Engine Power mode.

Conditions for Clearing the DTC
    • DTC P0121 is a type B DTC.
    • DTCs P0122, P0123, P0222, P0223 and P2135 is a type A DTC.

Diagnostic Aids

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

Connector End View Reference

Component Connector End Views

Description and Operation

Throttle Actuator Control (TAC) System Description

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Ignition ON, observe the DTC information with a scan tool. Verify DTC P06A3 is not set.
    2. ⇒If the DTC is set, refer to DTC P0641, P0651, P0697, or P06A3 .
  2. Ignition ON, observe both Throttle Position Sensor voltage parameters with a scan tool. Verify the scan tool Throttle Position Sensor 1 and 2 parameters are between 1.0-4.0 V.
  3. Perform the scan tool Throttle Sweep Test while observing the Throttle Position Sensors 1 and 2 Agree/Disagree parameter. The parameter should display Agree.
  4. Observe the DTC Information with a scan tool. DTCs  P0121, P0122, P0123, P0222, P0223, and P2135 should not set.
  5. 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 Q38 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 Ω between the low reference circuit terminal C and ground.
    3. ⇒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 K20 ECM.
  3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal E and ground.
    4. ⇒If less than the specified range, test the 5 V reference circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the K20 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 K20 ECM.
  4. Test for less than 1 V between the TP sensor 1 signal circuit terminal D and ground.
    5. ⇒If greater than specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  5. Test for 4.8-5.2 V between the TP sensor 2 signal circuit terminal F and ground.
    6. ⇒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 K20 ECM.
    ⇒If greater than specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the K20 ECM.
  6. 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.
    7. ⇒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 K20 ECM.
  7. If all circuits test normal, test or replace the Q38 throttle body assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

    •  Throttle Body Assembly Replacement : LF1 or LFW
    • Control Module References for ECM replacement, programming and setup
   


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