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Tahoe / Yukon Service Manual

DTC P0122, P0123, P0222, P0223, P2135, U0606, or U0607

Engine Controls and Fuel - 5.3L L84 or 6.2L L87 | Diagnostic Information and Procedures | Document ID: 5807069 DTC P0122, P0123, P0222, P0223, P2135, U0606, or U0607 Diagnostic Instructions Perform the Diagnostic System Check prior to using this diagnostic procedure: Diagnostic System Check - Vehicle Review the description of Strategy Based Diagnosis: Strategy Based Diagnosis An overview of each diagnostic category can be found here: Diagnostic Procedure Instructions DTC Descriptor DTC P0122 Throttle Position Sensor Circuit Low DTC P0123 Throttle Position Sensor Circuit High DTC P0222 Throttle Position Sensor 2 Circuit Low DTC P0223 Throttle Position Sensor 2 Circuit High DTC P2135 Throttle Position Sensor and Sensor 2 Correlation DTC U0606 Lost Communication with Throttle Position Sensor DTC U0607 Lost Communication with Throttle Position Sensor 2 Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
5 V Reference P06A3 U0606, U0607 P06A3 P0121, P2135*
Signal U0606, U0607 U0606, U0607 U0606, U0607 P0121, P2135*
Low Reference — U0606, U0607 — P0121, P2135*
* This DTC sets when there is an internal component issue: Q38 Throttle Body

Typical Scan Tool Data Throttle Position Sensor Short to Short to Circuit Ground Open Voltage Operating Conditions:

Circuit Short to Ground Open Short to Voltage
Accessories = Off Parameter Normal Range: 3.75 to 4.75 V
5 V Reference 5.0 V 5.0 V 5.0 V
Signal 5.0 V 0.0 V 0.0 V
Low Reference — 0.0 V —

Throttle Position Sensor 2

Circuit Short to Ground Open Short to Voltage
Operating Conditions: Engine = Running Accessories = Off Parameter Normal Range: 0.45 to 0.90 V
5 V Reference 0.0 V 0.0 V 0.0 V
Signal 0.0 V 5.0 V 5.0 V
Low Reference — 5.0 V —

Circuit/System Description For an overview of the component/system, refer to: Throttle Actuator Control (TAC) System Description

Circuit Description
5 V Reference Regulated voltage supplied by the control module.
Serial Data The control module input circuit has an internal resistance connected to 5 V. Digitally encoded information for communication between devices.
Low Reference Grounded through the control module.
Component Description
Q38 Throttle Body The assembly has several functions:
Component Description
The throttle valve is actuated by a bidirectional DC motor. A spring pulls the valve to a rest or default position, in which the valve is almost closed. The throttle actuator motor can push against the force of the spring to open or close the valve. The more current flow through the motor, the more the valve moves. The component Q38 contains a contactless inductive position sensor. A fixed transmitter coil excites a movable rotor, which in turn induces a current in a fixed receiver coil. The current varies with the angle of the rotor. Electronics inside the sensor convert the current into digital data which is transmitted via a serial data circuit to the control module K20.
K20 Engine Control Module The control module contains a microprocessor used to process input data to control outputs. The control module controls a series of actuators to ensure optimal engine performance. The control module does this by reading values from a variety of sensors, interprets the data and adjusts the engine actuators accordingly.

Conditions for Running the DTC { P0122, P0123, P0222, P0223 } DTC P06A3, U0606, U0607 = Not set { P2135 } DTC P0122, P0123, P0222, P0223, P06A3, U0606, U0607 = Not set Ignition and Start Signal = Greater than 6.4 V Ignition and Start Switch Signal = On or Engine = Running Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC P0122 Throttle Position Sensor = Less than 0.02 V — For greater than 1 s P0123 Throttle Position Sensor = Greater than 4.76 V — For greater than 1 s P0222 Throttle Position Sensor 2 = Less than 0.02 V — For greater than 1 s P0223 Throttle Position Sensor 2 = Greater than 4.6 V — For greater than 1 s P2135 Throttle Position Sensor & Throttle Position Sensor 2 = Not within 7-10% of each other — For greater than 1 s U0606, U0607 Serial data message from component: Q38 Throttle Body = Not Received — For greater than 1 s Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC — Additional actions taken: P16 Instrument Cluster = Reduced Acceleration Reduced Engine Power = Active Under certain conditions, the control module commands the engine Off. Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type A DTC Diagnostic Aids A high resistance condition on the component circuits may cause the DTC to set. If the accelerator pedal is pressed all the way down, the throttle blade angle and the scan tool Throttle Position angle parameter will only go to an angle less than 40%. Under cold start conditions, it might happen briefly that the desired and the actual throttle blade position do not match. Reference Information Schematic Reference Engine Controls Schematics Connector End View Reference Master Electrical Component List 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 Circuit/System Verification

  1. Ignition » On / Vehicle » In Service Mode
  2. Verify DTC P0601-P0606, P06A3, P16F3 is not set. ⇒ If any of the DTCs are set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If none of the DTCs are set
  3. Verify DTC P0122, P0123, P0222, P0223, P2135, U0606, U0607 is not set. ⇒ If only DTC P0122, P0123, P0222, P0223, P2135 is set Replace the component: Q38 Throttle Body ⇒ If DTC U0606, U0607 and one or more of the DTCs P0122, P0123, P0222, P0223, P2135 is set Refer to: Circuit/System Testing ⇓ If none of the DTCs are set
  4. Perform the scan tool control function: Throttle Sweep » Execute Control Sequence Verify the scan tool parameter: Throttle Position Sensor and Sensor 2 = Agree ⇒ If not the specified state Replace the component: Q38 Throttle Body ⇓ If the specified state
  5. Verify DTC P0122, P0123, P0222, P0223, P2135, U0606, U0607 is not set. ⇒ If any of the DTCs are set Refer to: Circuit/System Testing ⇓ If none of the DTCs are set
  6. Verify the scan tool parameter: Throttle Position Sensor & Throttle Position Sensor 2 = The value should not spike or drop out. Perform the action while monitoring the parameter: Wiggle the harness and connector: K20 Engine Control Module Wiggle the harness and connector: Q38 Throttle Body ⇒ If the value spikes or drops out Repair as necessary » Wiring / Terminal(s) / Electrical Connector(s) ⇓ If the value does not spike or drop out
  7. 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. Verify the DTC does not set. ⇒ If the DTC sets Refer to: Circuit/System Testing ⇓ If the DTC does not set
  8. All OK. Circuit/System Testing
  1. Ignition/Vehicle & All vehicle systems » Off
  2. Disconnect the electrical connector: Q38 Throttle Body
  3. Test for less than 5 Ω between the test points: Low Reference circuit terminal 4 & Ground ⇒ If 5 Ω or greater 3.1. Disconnect the appropriate electrical connector: K20 Engine Control Module 3.2. Test for less than 2 Ω between the test points: Low Reference circuit terminal 4 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇓ If less than 5 Ω
  4. Ignition » On / Vehicle » In Service Mode
  5. Test for 4.8 to 5.2 V between the test points: 5 V Reference circuit terminal 5 & Low Reference circuit terminal 4 ⇒ If less than 4.8 V 5.1. Ignition/Vehicle » Off 5.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 5.3. Test for infinite resistance between the test points: 5 V Reference circuit terminal 5 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 5.4. Test for less than 2 Ω between the test points: 5 V Reference circuit terminal 5 @ Component harness & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇒ If greater than 5.2 V 5.1. Ignition/Vehicle » Off 5.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 5.3. Ignition » On / Vehicle » In Service Mode 5.4. Test for less than 1 V between the test points: 5 V Reference circuit terminal 5 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇒ If less than 1 V » Replace the component: K20 Engine Control Module ⇓ If between 4.8 and 5.2 V
  6. Test for 4.8 to 5.2 V between the test points: Serial Data circuit terminal 3 & Ground ⇒ If less than 4.8 V 6.1. Ignition/Vehicle » Off 6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 6.3. Test for infinite resistance between the test points: Serial Data circuit terminal 3 @ Component harness & Ground ⇒ If less than infinite resistance » Repair the short to ground on the circuit. ⇓ If infinite resistance 6.4. Test for less than 2 Ω between the test points: Serial Data circuit terminal 3 & The other end of the circuit @ Control module harness ⇒ If 2 Ω or greater » Repair the open/high resistance in the circuit. ⇒ If less than 2 Ω » Replace the component: K20 Engine Control Module ⇒ If greater than 5.2 V 6.1. Ignition/Vehicle » Off 6.2. Disconnect the appropriate electrical connector: K20 Engine Control Module 6.3. Ignition » On / Vehicle » In Service Mode 6.4. Test for less than 1 V between the test points: Serial Data circuit terminal 3 @ Component harness & Ground ⇒ If 1 V or greater » Repair the short to voltage on the circuit. ⇓ If less than 1 V » Replace the component: K20 Engine Control Module ⇓ If between 4.8 and 5.2 V
  7. Test or replace the component: Q38 Throttle Body Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification Throttle Body Assembly Replacement — Q38 Throttle Body For control module replacement, programming, and setup refer to: Control Module References