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Tahoe / Yukon Service Manual

DTC P026A

Engine Controls and Fuel - 3.0L LM2 Diesel | Diagnostic Information and Procedures | Document ID: 5809035 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 P026A Charge Air Cooler Low Efficiency Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performanc
Signal — Terminal 1 @ B193A Charge Air Cooler Air Temperature Sensor - Inlet P007C P007D P007D* P007B, P007E, P026A
Signal — Terminal 2 @ B193A Charge Air Cooler Air Temperature Sensor - Inlet — P007D, P007E — P007B, P007E, P026A
Signal — Terminal 1 @ B193B Charge Air Cooler Air Temperature Sensor - Outlet P10D6 P10D7 P10D7* P026A, P10D5, P10D8
Signal — Terminal 2 @ B193B Charge Air Cooler Air Temperature Sensor - Outlet — P10D7 — P026A, P10D5, P10D8
* Component damage may occur if the circuit is shorted to B+.

Typical Scan Tool Data Charge Air Cooler Temperature Sensor & Charge Air Cooler Temperature Sensor 2

Circuit Short to Ground Open Short to Voltage
Operating Conditions: Engine = Idling — At normal operating temperature. Parameter Normal Range: Charge Air Cooler Temperature Sensor = 43 to 54°C (110 to 130°F) Charge Air Cooler Temperature Sensor 2 = 16 to 38°C (60 to 100°F)
Circuit Short to Ground Open Short to Voltage
Signal — Terminal 1 215°C (419°F) −40°C (−40°F) −40°C (−40°F)
Signal — Terminal 2 215°C (419°F) −40°C (−40°F) −40°C (−40°F)

Circuit/System Description For an overview of the component/system, refer to: Compressor Air Intake Turbocharger System Description

Circuit Description
Signal — Terminal 1 The control module input circuit has an internal resistance connected to 0.5 V.
Signal — Terminal 2 The control module input circuit has an internal resistance connected to 2.5 V.
Component Description
B193A Charge Air Cooler Air Temperature Sensor - Inlet B193B Charge Air Cooler Air Temperature Sensor - Outlet The temperature sensor is a negative temperature coefficient thermistor, a resistor which changes based on temperature.
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.

The charge air cooler efficiency is computed as a ratio between the following inputs: B9 Ambient Air Temperature Sensor B34K Charge Air Cooler Coolant Temperature Sensor - Inlet B193A Charge Air Cooler Air Temperature Sensor - Inlet B193B Charge Air Cooler Air Temperature Sensor - Outlet The diagnostic monitors the average temperature reduction ratio of the charge air cooler. Conditions for Running the DTC DTC P00C7, P00DF, P00E0-P00E2, P0071, P0072, P0073, P0074, P007B, P007C, P007D, P007E, P0101, P0102, P0103, P0106, P0107, P0108, P0119, P02E8, P02E9, P0502, P0503, P0722, P0723, P105D, P10D6, P10D7, P10D8, P122D, P2227, P2228, P2229, P2230, U060F, U0654 = Not set Ambient Air Temperature = Warmer than −9°C (16°F) Barometric Pressure Sensor = Greater than 70 kPa (10 PSI) Charge Air Cooler Coolant Pump Speed = Greater than 1,400 RPM Engine Coolant Temperature Sensor = Warmer than 60°C (140°F) Intake Air Flow Valve Position = Greater than 85% The following parameters are not within 50°C (90°F) of each other: – Charge Air Cooler Temperature Sensor – Charge Air Cooler Temperature Sensor 2 Vehicle Speed Sensor = Greater than 30 km/h (18.6 MPH) Frequency the DTC runs = Continuously — After the running conditions are met — Greater than 4  s Conditions for Setting the DTC The following parameters are not within 42% of each other: Charge Air Cooler Temperature Sensor Charge Air Cooler Temperature Sensor 2 Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type B DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type B DTC Reference Information Schematic Reference Engine Heating/Cooling 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 there are no DTCs set related to the following component/system: B34K Charge Air Cooler Coolant Temperature Sensor - Inlet B193A Charge Air Cooler Air Temperature Sensor - Inlet B193B Charge Air Cooler Air Temperature Sensor - Outlet M10 Charge Air Cooler Coolant Pump ⇒ If the DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If the DTC is not set
  3. Verify the following conditions do not exist: Incorrect fluid level or condition — Coolant @ Charge Air Cooler — Surge Tank » Refer to: Loss of Coolant Antifreeze Concentration — Incorrect » Refer to: Charge Air Cooling System Draining and Filling M10 Charge Air Cooler Coolant Pump — Abnormal noise / Leaking / Stuck On / Visible Damage Hoses / Lines @ Charge Air Cooler — Leaking / Loose Clamps / Visible Damage Hoses / Lines @ M10 Charge Air Cooler Coolant Pump — Leaking / Loose Clamps / Visible Damage ⇒ If a condition exists Repair or replace as necessary ⇓ If no condition exists
  4. Perform the following procedure/test: Component Testing Verify the procedure/test passes. ⇒ If the procedure/test does not pass Replace the appropriate component: B193A Charge Air Cooler Air Temperature Sensor - Inlet B193B Charge Air Cooler Air Temperature Sensor - Outlet ⇓ If the procedure/test passes
  5. Perform the scan tool control function: Charge Air Cooler Coolant Pump » Command the component to the maximum position/speed Verify a condition does not exist with the component: M10 Charge Air Cooler Coolant Pump — Turns Off – Perform the action while monitoring the parameter: Wiggle the harness and connector: M10 Charge Air Cooler Coolant Pump Wiggle the harness and connector: K20 Engine Control Module ⇒ If a condition exists Repair as necessary » Wiring / Terminal(s) / Electrical Connector(s) ⇓ If no condition exists
  6. 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 Repeat the procedure starting at step 1 ⇓ If the DTC is not set
  7. All OK. Component Testing
  8. Ignition/Vehicle » Off
  9. Disconnect the electrical connector: B193A Charge Air Cooler Air Temperature Sensor - Inlet B193B Charge Air Cooler Air Temperature Sensor - Outlet
  10. Test for 200 to 114,900 Ω between the test points: Low Reference terminal 1 & Signal terminal 2 ⇒ If not between 200 and 114,900 Ω Replace the component: B193A Charge Air Cooler Air Temperature Sensor - Inlet B193B Charge Air Cooler Air Temperature Sensor - Outlet ⇓ If between 200 and 114,900 Ω
  11. Verify the value is within the range listed in the table: Temperature Versus Resistance - Charge Air Cooler Temperature Sensor ⇒ If not in the specified range Replace the component: B193A Charge Air Cooler Air Temperature Sensor - Inlet B193B Charge Air Cooler Air Temperature Sensor - Outlet ⇓ If in the specified range
  12. Test for infinite resistance between the test points: Each terminal of the component & The component’s housing ⇒ If less than infinite resistance Replace the component: B193A Charge Air Cooler Air Temperature Sensor - Inlet B193B Charge Air Cooler Air Temperature Sensor - Outlet ⇓ If infinite resistance
  13. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Charge Air Cooler Air Temperature Sensor Replacement — B193A Charge Air Cooler Air Temperature Sensor - Inlet Charge Air Temperature Secondary Sensor Replacement — B193B Charge Air Cooler Air Temperature Sensor - Outlet Control Module References for engine control module replacement, programming, and setup