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Tahoe / Yukon Service Manual

DTC P189C

Automatic Transmission - 10L80 MHS MQC | Diagnostic Information and Procedures | Document ID: 5224811 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 P189C Transmission Range Command Message Performance Circuit/System Description

Circuit Description
Serial Data Digitally encoded information for communication between devices.
Component Description
K20 Engine Control Module 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.
K71 Transmission Control Module The control module receives information from a variety of sensors, switches and serial data information from other control modules. This information is used to control a combination of solenoid valves to obtain the correct line pressure, gear ratio and torque converter clutch operation.

Conditions for Running the DTC Ignition and Start Signal = 9 to 32 V Ignition and Start Switch Signal = On Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC Commanded state does not match the actual state 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 Automatic Transmission 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 there are no DTCs set related to the following component/system: LIN Bus ⇒ If a related DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If a related DTC is not set
  3. 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
  4. All OK. Circuit/System Testing
  1. Ignition/Vehicle » Off
  2. Disconnect the appropriate electrical connector: LIN Bus 1 K20 Engine Control Module K71 Transmission Control Module
  3. Ignition » On / Vehicle » In Service Mode
  4. Test for less than 1 V between the test points: Serial Data circuit terminal 31 @ K71 Transmission Control Module & The other end of the circuit ⇒ If greater than 1 V Repair the short to voltage on the circuit. ⇓ If less than 1 V
  5. Ignition/Vehicle » Off
  6. Test for infinite resistance between the test points: Serial Data circuit terminal 31 @ K71 Transmission Control Module & Ground ⇒ If less than infinite resistance Repair the short to ground on the circuit. ⇓ If infinite resistance
  7. Test for less than 10 Ω between the test points: Serial Data circuit terminal 31 @ K71 Transmission Control Module & The other end of the circuit ⇒ If greater than 10 Ω Repair the open/high resistance in the circuit. ⇓ If less than 10 Ω
  8. Replace the component: K71 Transmission Control Module
  9. Verify the DTC does not set. ⇒ If the DTC sets Replace the component: K20 Engine Control Module ⇓ If the DTC does not set
  10. All OK. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair: Diagnostic Repair Verification For control module replacement, programming, and setup refer to: Control Module References