Buick Regal: DTC B1277 (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 provide an overview of each
diagnostic category.
DTC Descriptors
DTC B1277 02
Cellular Phone Microphone Circuit Short to Ground
DTC B1277 04
Cellular Phone Microphone Circuit Open/High Resistance
Diagnostic Fault Information
Circuit/System Description
The radio provides the cellular phone microphone with a supplied voltage on
the cellular phone
microphone high signal circuit. When the microphone is in use, voice data from
the user is sent back to
the radio on the cellular microphone low signal circuit.
Conditions for Running the DTC
- The ignition must be in the RUN or ACC position/vehicle in Service Mode.
- The system voltage is at least 9.5 V and no more than 15.5 V.
- All the above conditions are present for greater than 10 s.
Conditions for Setting the DTC
B1277 02
The radio detects a short to ground in the cellular phone microphone high
signal circuit for 10 s or
greater.
B1277 04
The following conditions will set this DTC:
- The radio detects an open/high resistance in the cellular phone
microphone high signal circuit for
10 s or greater.
- The radio detects an open/high resistance in the microphone low signal
circuit for 10 s or greater.
Action Taken When the DTC Sets
- The radio will not receive a signal from the cellular phone microphone.
- Calls can be placed but the caller cannot be heard.
Conditions for Clearing the DTC
- The condition responsible for setting the DTC no longer exists.
- 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
Circuit/System Testing
1. Ignition OFF/vehicle OFF, disconnect the harness connector at the B24
Cellular Phone
Microphone, ignition ON/vehicle in Service Mode.
2. Test for 9-11 V between the signal circuit terminal B 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 in the
circuit.
- 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.
- Go to next step: If less than 1 V, replace the A11 Radio.
- Go to next step: If between 9-11 V
3. Test for less than 1 V between the low reference circuit terminal A and
ground.
- 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
low reference
circuit and ground.
- If 1 V or greater, repair the short to voltage in the circuit.
- If less than 1 V, replace the A11 Radio
- Go to next step: If less than 1 V
4. Test for greater than 9 V between the signal circuit terminal B and the
low reference circuit
terminal A.
- Ignition OFF/vehicle OFF, disconnect the X1 harness connector at the A11
Radio.
- Test for infinite resistance between the low reference circuit and
ground.
- If less than infinite resistance, repair the short to ground in the
circuit.
- 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.
- Go to next step: If greater than 9 V
5. Test or replace the B24 Cellular Phone Microphone.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair.
- Refer to Mobile Telephone Microphone Replacement
- Refer to Control Module References for telematics communication
interface control module
replacement, programming and setup.
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
SEE MORE:
Calibration (without UGN)
NOTE: Do NOT swap cameras between vehicles, it is not approved and a
VIN
mismatch will occur.
The calibration process for the front view camera system is necessary when a
front view camera module
is replaced by a new one. This process is required anytime the module is rem
HUD System
The windshield is part of the HUD
system. If the windshield needs to
be replaced, be sure to get one that
is designed for HUD or the HUD
image may look out of focus.
Driver Assistance Systems
If the windshield needs to be
replaced and the vehicle is
equipped with a front camera sensor
for