AutoCodes – Buick – B127B Buick

B127B Buick Code - Rearview Camera Input Signal Circuit

Quick Answer

When the transmission is placed into R, a 12 V signal is sent to the Rearview Camera indicating that camera operation is requested. Common causes include Faulty Rearview Camera, Rearview Camera harness is open or shorted, Rearview Camera circuit poor electrical connection. Severity is Moderate - service should be scheduled soon. The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

What it means: B127B Buick indicates Rearview Camera Input Signal Circuit.
Common causes: Common causes include Faulty Rearview Camera, Rearview Camera harness is open or shorted, Rearview Camera circuit poor electrical connection.
Severity: Moderate - service should be scheduled soon.
Can I drive?: The vehicle may still be drivable for short trips if it runs normally, but avoid hard driving and repair it soon.

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Code Popularity 2,091

How popular is this code, among other codes? Low

Repair Importance Level

Moderate (Service soon) (2 / 3)

Repair Difficulty Level

Intermediate (2 / 3)

What is this?

Table of contents Created and updated by William Orellana on Nov 29, 2024

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code B127B Buick Description

When the transmission is placed into R, a 12 V signal is sent to the Rearview Camera indicating that camera operation is requested. Ignition voltage and ground are supplied to the Rearview Camera. The Rearview Camera sends a video image to the Human Machine Interface Control Module Bypass Module through a video signal + and a video signal − circuit. The Human Machine Interface Control Module Bypass Module passes the video image to Human Machine Interface Control Module via video signal + and a video signal − circuits. The Human Machine Interface Control Module Bypass Module is used to ensure the Human Machine Interface Control Module produces a quality rear vision camera image to be displayed on the Info Display Module when the vehicle is placed in reverse gear. In the event, the Human Machine Interface Control Module Bypass Module detects an issue with the camera image generated by the Human Machine Interface Control Module, such as black, solid color, frozen, or image other than the camera image, the Human Machine Interface Control Module Bypass Module will assume control of the image to the Info Display Module and displays a raw camera image with no park assist projection lines or object detection symbols for the entire reverse cycle.
The Human Machine Interface Control Module Bypass Module is part of the video signal + and a video signal − circuits path from the Rearview Camera to the Human Machine Interface Control Module as well as the digital Low Voltage Differential Signaling (LVDS) path (USB cable) between the Human Machine Interface Control Module and Info Display Module and needs to be active for either signal to be received by these modules. The Human Machine Interface Control Module Bypass Module is not connected to serial data and uses the reverse lamp voltage input to determine the vehicle gear state.
The Diagnostic Trouble Code (DTC) will be set when the video signal from the rearview camera has not been received by the Radio for 2.5 s.

OBDII Code B127B Buick - Rearview Camera Input Signal Circuit - AutoCodes.com — B127B Buick Code - Rearview Camera Input Signal Circuit

What does this mean?

What are the Possible Causes of the DTC B127B Buick?

Faulty Rearview Camera
Rearview Camera harness is open or shorted
Rearview Camera circuit poor electrical connection
Faulty Human Machine Interface Control Module
Faulty Info Display Module

How to Fix the DTC B127B Buick?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What does this mean?

Code Tech Notes

A poor video image can be caused by ice, snow, and mud buildup on the lens of the Rearview Camera. Also, extreme lighting conditions can affect performance, such as operating in the dark or with bright sunlight shining on the camera. Extreme high or low temperatures can also affect image quality. An open or high resistance in the shield of the video signal circuit can also cause a distorted screen.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the B127B Buick code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about B127B Buick Code

What does the OBDII code B127B mean for my Buick?

The B127B code indicates a problem with the rearview camera input signal circuit, which may affect the operation of the rearview camera system.

What are common symptoms associated with the B127B code?

Common symptoms include a malfunctioning rearview camera, a blank display when the vehicle is in reverse, or warning messages on the dashboard related to the camera system.

What could cause the B127B code to trigger?

Possible causes include a faulty rearview camera, damaged wiring or connectors in the camera circuit, or issues with the body control module (BCM).

How can I diagnose the cause of the B127B code?

You can start by checking the rearview camera and its connections for any visible damage, ensuring that the wiring harness is intact, and using a multimeter to test for proper voltage and continuity.

Are there any common repair tips for fixing the B127B code?

Repair tips include repairing or replacing damaged wiring, ensuring all connectors are secure and free of corrosion, and replacing the rearview camera if itâ€™s found to be defective.

Will clearing the B127B code fix the problem permanently?

Clearing the code may temporarily turn off the warning light, but the underlying issue must be fixed for the problem to be resolved permanently.

Can I drive my Buick safely with the B127B code?

While it may be safe to drive, the lack of a functioning rearview camera can pose a safety risk when reversing, so itâ€™s advisable to address the issue promptly.

How much does it typically cost to repair the B127B code?

Repair costs can vary widely depending on the specific issue, but you may expect to pay anywhere from $100 to $500 for diagnosing and repairing wiring issues or replacing the camera.

Is this code specific to Buick vehicles?

No, the B127B code can appear in various General Motors vehicles, not just Buicks, as it relates to the rearview camera input signal circuit common to many models.