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Tahoe / Yukon Service Manual

DTC B1B79

Cellular, Entertainment, and Navigation | Diagnostic Information and Procedures | Document ID: 5835284 Diagnostic Instructions Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach. Diagnostic Procedure Instructions provides an overview of each diagnostic category. DTC Descriptor DTC B1B79 Center Stack Low Voltage Differential Signaling LVDS Signal (+) circuit For symptom byte information refer to: Symptom Byte List Diagnostic Fault Information

Circuit Circuit Function Short to Ground Open/High Resistance Short to Voltage Signal Performan
LVDS Cable Digital Video B1B79 11 B1B79 13 — —

Circuit/System Description The infotainment display and controls are a separate component from the A11 Radio, combined into an assembly called the A22 Radio Control. The assembly is supplied battery voltage and ground from the vehicle harness. The A11 Radio communicates digital video data for on-screen display through a dedicated cable containing the LVDS data circuits. If the A11 Radio (Center Stack Module) detects the A22 Radio Control is not responding to the output on the LVDS circuits, the A11 Radio sets the DTC. Conditions for Running the DTC Ignition ON The system voltage is 9-16 V The infotainment system is ON The test is continuously running when the infotainment system is operating Conditions for Setting the DTC B1B79 11 The A11 Radio detects a short to ground diagnostic status on the LVDS circuits. B1B79 13 The A11 Radio detects an open diagnostic status on the LVDS circuits. Action Taken When the DTC Sets The A11 Radio sets this DTC No images are shown on the A22 Radio Control. Conditions for Clearing the DTC g The A11 Radio detects a properly synced digital video signal. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred. Diagnostic Aids Malfunctions may include a flickering or distorted screen or a blank screen. A momentary spike in volume upon start up may be due to the radio accessing the guest profile before switching to an established customer user profile. The radio will remember the set volume level the last time it was shut down in the guest profile mode, which is a normal operating characteristic. To alleviate the issues turn the radio on and proceed to the guest profile. Turn the volume level down to a lower level and power down the vehicle, the radio will retain the lower volume level upon the next start up. Reference Information Schematic Reference Radio/Navigation System Schematics Connector End View Reference Master Electrical Component List Description and Operation Radio/Audio System Description and Operation Electrical Information Reference Circuit Testing Connector Repairs Testing for Intermittent Conditions and Poor Connections Wiring Repairs Scan Tool Reference Control Module References for scan tool information Circuit/System Verification

  1. Verify no DTCs are present. ⇒ If any DTCs are present Refer to Diagnostic Trouble Code (DTC) List - Vehicle. ⇓ If no DTCs are present
  2. Ignition ON/vehicle in service mode, infotainment system ON, verify the Info Display shows an image. ⇒ If the Info Display does not show an image. Refer to Circuit/System Testing. ⇓ If the Info Display does show an image.
  3. All OK Circuit/System Testing
  4. Verify the LVDS interface cable is properly connected at the A22 Radio Control and the A11 Radio and there is no damage to the cable or connections.
  5. Ignition ON/vehicle in service mode, infotainment system ON.
  6. Verify the A22 Radio Control displays an image. ⇒ If the A22 Radio Control does not display an image. Replace LVDS interface cable from the A22 Radio Control to the A11 Radio. 3.1. Ignition ON/vehicle in service mode, infotainment system ON. 3.2. Verify the A22 Radio Control displays an image. ⇒ If the A22 Radio Control does not display an image. Replace the A22 Radio Control. 3.3. Ignition ON/vehicle in service mode, infotainment system ON. 3.4. Verify the A22 Radio Control displays an image. ⇒ If the A22 Radio Control does not display an image. Replace the A11 Radio. ⇓ If the A22 Radio Control displays an image A fault is currently not present and may be an intermittent condition. ⇓ If the A22 Radio Control displays an image.
  7. A fault is currently not present and may be an intermittent condition. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. For control module replacement, programming, and setup refer to: Control Module References