Buick Regal: DTC B124B (without IO5/IO6)

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 B124B

USB 1 Circuit

For symptom byte information refer to Symptom Byte List.

Diagnostic Fault Information

1. USB port Inoperative
2. Fault may affect one or more components, dependent on fault location
3. Fault affects multiple components, dependent on vehicle equipment

Circuit/System Description

The infotainment system has a auxiliary jack and USB receptacle assembly. The auxiliary jack and USB receptacle assembly receives fused battery voltage and ground from the harness to power the internal hub device as well as providing additional amperage to power USB devices. The internal hub device interfaces directly with the radio via a standard USB cable.

Auxiliary Audio Input Jack (if equipped)

When a portable audio playback device is connected to the 3.5 mm (1/8 in.) auxiliary audio input jack an internal switch opens the detection signal circuit. The radio detects the device and AUX becomes available as an audio source. Audio signals from the device are sent to the radio from the auxiliary input jack via the left, right, and common audio signal circuits.

USB Port

The USB receptacle interfaces directly with the radio via a standard USB cable. A Mini type USB connector is used to connect the cable at the radio and at the auxiliary jack and USB receptacle assembly. USB male to female connections are typically used for connecting USB cables together where an in-line connection is required. An in-line cable connection is typically found between the console and I/P harness.

The USB port allows connectivity to the infotainment system from portable media players or a USB storage device (memory stick/ flash drive). When a device is connected to the USB port, the system detects the device and USB becomes available as an audio source. Once connected, the device can be controlled from the radio controls.

Not all portable media player devices or file types are compatible. Refer to the vehicle owner's manual for information on USB devices, control, and operation.

SD Card Reader (if equipped)

The infotainment system uses the SD Card Reader for the navigation map data when equipped.

Refer to the owner manual for information on the navigation system.

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 per second when the infotainment system is operating

Conditions for Setting the DTC

The radio detects an excessive current condition on the USB 5 V circuit.

Action Taken When the DTC Sets

The USB port is inoperative while the DTC is current.

Conditions for Clearing the DTC

• The condition for setting the DTC is no longer present.
• A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

This DTC may be set due to the connection of an incompatible or faulty USB device.

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-50334-50 USB Cable and Adapter Kit
• EL-50334-14 Infotainment Test Cable

Circuit/System Verification

1. Verify DTC B124B is not set. Since occurrences of this DTC can be caused by an incompatible or faulty USB device, review with the customer the conditions under which their concern occurred.

• If DTC B124B is set.

Refer to Circuit/System Testing.

• Go to next step: If DTC B124B is not set.

2. Ignition ON, infotainment system ON.

3. Connect a compatible USB device to the USB port and attempt to play audio from a comparable know good vehicle.

4. Verify audio is heard through the infotainment system while operating the USB device.

• If audio is not heard

USB device is not compatible, try a different USB device.

• Go to next step: If audio is heard

5. Connect a compatible USB device to the USB port and attempt to play audio from the customers vehicle.

6. Verify audio is heard through the infotainment system while operating the USB device.

• If audio is not heard

Refer to Circuit/System Testing

• Go to next step: If audio is heard

Go to next step: All OK

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the X83 Auxiliary Audio Input.

2. Test for less than 10 Ω between the ground circuit terminal 4 and ground.

• If 10 Ω or greater

1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit 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. Verify that a test lamp illuminates between the B+ circuit terminal 6 and ground.

• If the test lamp does not illuminate

1. Ignition OFF, remove the test lamp.
2. Test for less than 2 Ω in the B+ circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.

• Go to next step: If the test lamp illuminates

4. Verify the USB cable is properly connected at all components and any in-line connections, and there is no damage to the cable or connections.

• If connection problems or cable damage is noted.

Perform the appropriate repair or replacement to correct any issues.

• Go to next step: If no connection problems or cable damage is noted.

5. Replace the X83 Auxiliary Audio Input. Connect all harness connectors.

6. Ignition ON, infotainment system ON.

7. Connect a compatible USB device to the USB port and attempt to play audio.

8. Verify audio is heard through the infotainment system while operating the USB device.

• If audio is not heard

1. Replace the USB cable.
2. Connect a compatible USB device to the USB port and attempt to play audio.
3. Verify audio is heard through the infotainment system while operating the USB device.
   • If audio is not heard, replace the A11 Radio.
   • Go to next step: If audio is heard.
4. All OK.

• Go to next step: If audio is heard

9. All OK.

Repair Instructions

• Refer to Audio Disc Player and USB Receptacle Replacement.
• Refer to Control Module References control module replacement, programming, and setup.
• Perform the Diagnostic Repair Verification after completing the repair.

DTC B124F

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 B124F

Universal Serial Bus (USB) Programming

For symptom byte information, refer to Symptom Byte List.

Circuit/System Description

Certain devices in the entertainment system must be programmed with specific software and other information to operate correctly. This DTC is the result of an unsuccessful USB programming event of the device. The symptom byte information is for engineering reference only. No external circuit diagnosis is involved

Conditions for Running the DTC

Once upon each USB Programming Event.

Conditions for Setting the DTC

The programming event was incomplete, or completed with errors.

Action Taken When the DTC Sets

The entertainment system has limited or no functionality.

Conditions for Clearing the DTC

The programming event completes successfully.

Diagnostic Aids

DTC B124F could set if a programming attempt was made when the module already had the latest update available installed.

Circuit/System Verification

1. Ignition ON/vehicle in Service Mode.

2. Verify DTC B124F is not set.

• If DTC B124F is set

1. Program the device that set the DTC.
2. Verify the DTC does not set.
   • If DTC is set, replace the device that set the DTC.
   • Go to next step: If the DTC is not set
3. All OK.

• Go to next step: If DTC B124F is not set

3. All OK

Repair Instructions

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

Perform the Diagnostic Repair Verification after completing the repair.

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