Buick Regal: DTC B123E
Diagnostic Instructions
- Perform the Diagnostic System Check prior to using this diagnostic
procedure: Diagnostic
System Check - Vehicle
- Review the description of Strategy Based Diagnosis: Strategy Based
Diagnosis
- An overview of each diagnostic category can be found here: Diagnostic
Procedure Instructions
DTC Descriptor
DTC B123E
Radio Keypad Button Signal Circuit
Symptom Byte Information: Symptom Byte List.
Diagnostic Fault Information
1. Radio Control buttons inoperative
Circuit/System Description
The radio controls communicate radio control inputs directly to the radio
through a discrete circuit for
volume up, volume down and power button. It also uses a series of resistors
through a 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. Messages communicated between the
radio and the radio
controls include the following:
- Button presses/knob rotations
- Commands for the state of indicators
- Controls back-lighting
Conditions for Running the DTC
- Vehicle in Service Mode/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 250 ms when the infotainment system is
operating
Conditions for Setting the DTC
B123E 01
The radio detects an open/high resistance or short to voltage on the radio
controls key signal circuit
B123E 02
The radio detects a short to ground on the radio controls key signal circuit
Actions Taken When the DTC Sets
Radio control buttons will be inoperative
Conditions for Clearing the DTC
The condition for setting the DTC is no longer detected for 250 ms.
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
Circuit/System Verification
1. Ignition On/vehicle in Service Mode.
2. Verify that each button on the A22 radio controls operates normally by
pressing each button
individually.
- If none of the buttons operate normally
Refer to Circuit/System Testing
- If some, but not all, of the buttons operate normally
Test or replace the A22 radio controls
- Go to next step: If all of the buttons operate normally
3. All OK.
Circuit/System Testing
1. Ignition OFF/vehicle OFF and all vehicle systems OFF. Disconnect the
harness connector at the
A22 radio controls. It may take up to 2 min for all vehicle systems to power
down.
2. Test for less than 10 Ω between the following circuits and ground.
- Ground return terminal 2
- Low reference terminal 8
- If 10 Ω of greater
- Ignition OFF/vehicle OFF, disconnect the X1 harness connector at the P17
Info Display
Module.
- Test for less than 2 Ω in the 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.
4. Test for 2.5 - 3.5 V on the signal circuit terminal 3 @ the A 22 Radio
Controls and ground.
- Ignition OFF/vehicle OFF, disconnect the X1 harness connector at the A11
Radio.
- Test for infinite resistance between the signal circuit and ground.
- If less than infinite resistance, repair the short to ground.
- Go to next step: If infinite resistance
- Test for less than 2 Ω in 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.
- Ignition OFF/vehicle OFF, disconnect the X1 harness connector at the A11
Radio.
- Ignition ON/vehicle in Service Mode, test for less than 1 V between the
signal circuit and
ground.
- If 1 V or greater, repair the short to voltage on the circuit.
- If less than 1 V, replace the A11 radio.
- Go to next step: If between 2.5 - 3.5 V
5. Test or replace the A22 Radio Controls.
Repair Instructions
READ NEXT:
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.
Refe
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.
Refe
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.
Refe
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