Buick Regal: Radio Controls 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. Home, Seek Up, Seek Down, and/or Phone button will not function
2. Power Button will not function
3. Unable to adjust volume
4. All Radio Control buttons may 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.

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 B123E is not set.

• If DTC B123E is set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

• Go to next step: If DTC B123E is not set

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

3. Verify that all radio controls operate and perform the correct function.

• If all or some of the radio controls are inoperative

Refer to Circuit/System Testing.

• Go to next step: If all radio controls operate and perform the correct function.

4. All OK.

Circuit/System Testing

1. Ignition OFF/vehicle OFF, disconnect the harness connector at the A22 Radio Controls.

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

• terminal 2
• terminal 8
• If 10 Ω or greater

1. Disconnect the X1 harness connector at the P17 Info Display Module.
2. Test for less than 2 Ω in the low reference circuits end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the P17 Info Display Module.

• Go to next step: If less than 10 Ω

3. Ignition ON/vehicle in Service Mode, test for 2.5 - 3.5 V between the following signal circuit terminals and ground:

• terminal 3
• terminal 4
• terminal 6
• terminal 7
• If less than 2.5 V

1. Ignition OFF/vehicle OFF, disconnect the X2 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.

• If greater than 3.5 V

1. Ignition OFF/vehicle OFF, disconnect the X2 harness connector at the A11 Radio.
2. Test for less than 1 V between the control 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 2.5 - 3.5 V

4. Replace the A22 Radio Controls

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for radio or radio control assembly replacement, programming, and setup.

READ NEXT: