Buick Regal: Radio Information Display Malfunction (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.

Diagnostic Fault Information

1. Display blank
2. Touch screen does not function

Circuit/System Description

The radio info display module, radio controls and radio are all separate components. The radio controls communicate radio control inputs directly to the radio through a discrete circuit for volume up, volume down and power ON button. It also uses a series of resistors through a single signal circuit when the home, seek up, seek down and phone buttons are pressed. After receiving the message the radio will perform the requested function. The info display module receives digital video data from the radio for on-screen display information through the LVDS (Low Voltage Differential Signal) cable. The radio communicates with the info display module over the radio display touch interrupt request signal for touch screen inputs.

Diagnostic Aids

Malfunctions may include a flickering or distorted image or a blank screen

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.

Circuit/System Verification

1. Verify DTC B127E is not set.

• If DTC B127E is set.

Refer to Diagnostic Trouble Code (DTC) List - Vehicle.

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

2. Ignition ON/vehicle in Service Mode, A11 Radio ON.

3. Verify the P17 Info Display Module turns on and information is shown on the display.

• If the P17 Info Display Module does not turn on, or information is not shown clearly in the display.

Refer to Circuit/System Testing - Blank Screen

• Go to next step: If the P17 Info Display Module turns on and information is shown on the display.

4. Verify the touch screen feature functions by touching a selection on the display.

• If the display does not respond to the touch screen selection

Refer to Circuit/System Testing - Touch Screen

• Go to next step: If the display responds to the touch screen selection

5. All OK.

Circuit/System Testing

Blank Screen

1. Ignition OFF/vehicle OFF and all vehicle systems OFF, disconnect the X1 harness connector at the P17 Info Display Module. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between the following ground circuit terminals and ground:

• terminal 9
• terminal 10
• If 10 Ω or greater

1. Test for less than 2 Ω in the ground circuits end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than, 2 Ω repair the open/high resistance in the ground connection.

• Go to next step: If less than 10 Ω

3. Ignition ON/vehicle in Service Mode.

4. Test for 5 V or greater between control circuit terminal 1 and ground.

• If less than 5 V

1. Ignition OFF/vehicle OFF, disconnect the X1 harness connector at the A11 Radio.
2. Test for infinite resistance between the control circuit and ground.
   • If less than infinite resistance repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω on the control circuit end to end.
   • If 2 Ω or greater repair the open/high resistance in the circuit.
   • If less than 2 Ω replace the A11 Radio.

• Go to next step: If 5 V or greater.

5. Disconnect the harness connector at the A22 Radio Controls.

6. Test for infinite resistance between the P17 Info Display Module harness connector X1 terminal 3 and ground.

• If less than infinite resistance repair the short to ground on the circuit.
• Go to next step: If infinite resistance.

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

8. 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.

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

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

11. Verify the P17 Info Display Module displays an image.

• If the P17 Info Display Module does not display an image

1. Engine running, parking brake applied, transmission in REVERSE.
2. Verify the P17 Info Display Module displays a rear view image.
   • If the P17 Info Display Module displays a rear view image, replace the A11 Radio.
   • Go to next step: If the P17 Info Display Module does not display a rear view image.
3. Replace the P17 Info Display Module.
4. Ignition ON, infotainment system ON.
5. Verify the P17 Info Display Module displays an image.
   • If the P17 Info Display Module still does not display an image, replace the A11 Radio.
   • Go to next step: If the P17 Info Display Module displays an image.
6. All OK.

• Go to next step: If the P17 Info Display Module displays an image.

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

Touch Screen

1. Ignition OFF/vehicle OFF and all vehicle systems OFF, disconnect the X1 harness connector at the P17 Info Display Module. It may take up to 2 min for all vehicle systems to power down.

2. Ignition ON/vehicle in Service Mode.

3. Test for 1.5 - 2 V between the signal circuit terminal 7 and ground.

• If less than 1.5 V

1. Ignition OFF/vehicle OFF, disconnect the X2 harness connector at the A11 radio.
2. Test for infinite resistance between the signal circuit and ground.
   • If less than infinite resistance repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω on the signal circuit end to end.
   • If 2 Ω or greater repair the open/high resistance in the circuit.
   • If less than 2 Ω replace the A11 Radio.

• If greater than 2 V

1. Ignition OFF/vehicle OFF, disconnect the X2 harness connector at the A11 Radio.
2. Test for less than 1 V between the signal circuit and ground.
   • If greater than 1 V repair the short to voltage in the circuit.
   • If less than 1 V replace the A11 Radio.

• Go to next step: If between 1.5 - 2 V

4. Replace the P17 Info Display Module

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

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

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