Skip to content
Tahoe / Yukon Service Manual

DTC P1775

Automatic Transmission - 10L80 MHS MQC | Diagnostic Information and Procedures | Document ID: 5224790 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 P1775 Transmission Range Request Signal Message Counter Incorrect Circuit/System Description Control modules connected to the serial data circuits monitor the communication during normal vehicle operation. Operating information and commands are exchanged among the control modules. Each module on the serial data circuit maintains a transmit error counter and a receive error counter. The counter values increase with detected errors and decrease with error-free messages. 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 Serial Data = Message Counter Incorrect — Between the following control modules: K20 Engine Control Module K71 Transmission Control Module Within 10 consecutive messages, 10 have had an incorrect value. Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type A DTC The control module K20 uses the redundant information from control module K71 to determine the gear selector lever position. Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type A DTC Reference Information 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: Serial Data ⇒ If a related DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇒ If a related DTC is not set 2.1. Ignition/Vehicle » Off 2.2. Replace the component: K20 Engine Control Module 2.3. Operate the vehicle within the Conditions for Running the DTC. 2.4. Verify the DTC does not set. ⇒ If the DTC sets » Replace the component: K71 Transmission Control Module ⇓ If the DTC is not set 2.5. All OK. ⇓ If no DTC is set
  3. 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