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Tahoe / Yukon Service Manual

DTC P18F2

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 P18F2 Passenger Compartment Warm Up 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 = On — For greater than 3 s Serial Data = Enabled Frequency the DTC runs = Continuously — After the running conditions are met Conditions for Setting the DTC Serial Data = Message Counter Incorrect — Control module that has set the DTC The above condition(s) must occur 5 times. Actions Taken When the DTC Sets DTCs listed in the DTC Descriptor category = Type C DTC Conditions for Clearing the DTC DTCs listed in the DTC Descriptor category = Type C 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 ⇒ If a related DTC is set Refer to: Diagnostic Trouble Code (DTC) List - Vehicle ⇓ If a related DTC is not set
  3. Clear the DTCs.
  4. Operate the vehicle within the Conditions for Running the DTC. Verify the DTC does not set. ⇒ If the DTC sets 4.1. Ignition/Vehicle » Off 4.2. Replace the component: K20 Engine Control Module 4.3. Operate the vehicle within the Conditions for Running the DTC. Verify the DTC does not set. ⇒ If the DTC sets Replace the component: K71 Transmission Control Module ⇓ If the DTC does not set 4.4. All OK. ⇓ If the DTC does not set
  5. 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