Buick Regal: DTC B127E (IOB)

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.
• Refer to Diagnostic Procedure Instructions for an overview of each diagnostic category.

DTC Descriptor

DTC B127E 00

Front Video Display Output Signal Malfunction

DTC B127E 01

Front Video Display Output Signal Short to Battery

Diagnostic Fault Information

Circuit/System Description

The infotainment display and controls are separate components from the radio. The components are supplied battery voltage and ground from the vehicle harness. The radio communicates digital video data for on-screen display through a dedicated cable containing the LVDS data circuits.

If the radio detects the display is not responding to the output on the LVDS circuits, the radio sets the DTC.

Conditions for Running the DTC

• Ignition is ON or in the ACC position
• The system voltage is 9-16 V
• The infotainment system is ON
• The test is run once every 14 ms when the infotainment system is operating

Conditions for Setting the DTC

The radio detects the display is not responding to the output on the LVDS circuits.

Action Taken When the DTC Sets

• The radio sets this DTC
• No images are shown on the info display module

Conditions for Clearing the DTC

• The radio detects a properly synced digital video signal.
• A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Radio/Navigation System Wiring Schematics (IOB) , Radio/Navigation System Wiring Schematics (IOR) or Radio/Navigation System Wiring Schematics (IO5/IO6) , or Radio/Navigation System Wiring Schematics (IOS/IOT).

Connector End View Reference

Component Connector End View Index

Description and Operation

Radio/Audio System Description and Operation (IO6) , Radio/Audio System Description and Operation (IOB) , or Radio/Audio System Description and Operation (IOS/IOT/IOU).

Electrical Information Reference

• Refer to Circuit Testing
• Refer to Connector Repairs
• Refer to Testing for Intermittent Conditions and Poor Connections
• Refer to Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information.

Special Tools

• EL-50334 - 2 Type A female to Mini B male USB Cable
• EL-50334 - 14 Infotainment Test Cable

Circuit/System Testing

1. Vehicle OFF/Ignition OFF, disconnect the X1 harness connector at the P17 Info Display Module.

2. Test for infinite resistance between the signal circuits listed below and ground:

• Radio display LVDS lock signal circuit terminal 5
• Radio display LVDS error signal circuit terminal 6
• If less than infinite resistance

Repair the short to ground on the circuit.

• Go to next step: If infinite resistance

3. Reconnect the X1 harness connector at the P17 Info Display Module.

4. Disconnect the LVDS interface cable from the P17 Info Display Module.

5. Connect the EL-50334-2 Type A female to Mini B male USB Cable to the P17 Info Display Module. Connect the EL-50334-14 Infotainment Test Cable to the adapter.

6. Disconnect the LVDS interface cable from the A11 Radio. Connect the EL-50334 - 14 Infotainment Test cable to the A11 Radio.

7. Ignition ON/Vehicle in Service Mode, infotainment system ON.

8. Verify DTC B127E is not set as current.

• If DTC B127E is set as current

1. Replace the P17 Info Display Module. Connect all harness connectors.
2. Ignition ON, infotainment system ON.
3. Verify DTC B127E is not set as current.
   • If DTC B127E is still set as current, replace the A11 Radio.
   • Go to next step: If DTC B127E is not set.
4. All OK.

• Go to next step: If DTC B127E is not set as current.

9. Replace the vehicle LVDS interface cable from the P17 Info Display Module to the A11 Radio.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Refer to Control Module References for replacement, programming, and setup.

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