AutoCodes – GMC – B127B GMC

B127B GMC 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 GMC 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 7,060

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

What does this mean?

What are the Possible Causes of the DTC B127B GMC?

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 GMC?

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 GMC 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.

Need more information about the B127B GMC code?

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Need Help with the Code?

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Information for Specific GMC Models

B127B 2014 GMC Sierra — Rearview Camera Input Signal Circuit
B127B 2015 GMC Sierra — Rearview Camera Input Signal Circuit
B127B 2016 GMC Sierra — Rearview Camera Input Signal Circuit
B127B 2017 GMC Sierra — Rearview Camera Input Signal Circuit
B127B 2018 GMC Sierra — Rearview Camera Input Signal Circuit

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 GMC Code

1. What are the common symptoms of OBDII code B127B GMC (Rearview Camera Input Signal Circuit)?

- Common symptoms include a malfunctioning rearview camera, distorted or no image display on the screen, and intermittent camera operation.

2. What can cause the OBDII code B127B GMC to trigger?

- The code B127B GMC is typically triggered by issues with the rearview camera system, such as faulty wiring, a defective camera, or a damaged camera input signal circuit.

3. How can I diagnose the root cause of the B127B GMC code related to the rearview camera input signal circuit?

- Diagnosis involves checking the rearview camera connections, inspecting the wiring for damage or corrosion, testing the camera functionality, and using a diagnostic scanner to analyze the camera input signal circuit.

4. Is it safe to continue driving with the OBDII code B127B GMC active?

- It is generally safe to drive with the B127B GMC code, but it is recommended to address the issue promptly to ensure proper functionality of the rearview camera system.

5. What are some repair tips for fixing the B127B GMC code associated with the rearview camera input signal circuit?

- Repair tips include checking and repairing any damaged wiring, replacing a faulty rearview camera, resetting the system by disconnecting the battery, and clearing the trouble codes with a diagnostic scanner.

6. Can a DIY enthusiast fix the B127B GMC code related to the rearview camera input signal circuit?

- Depending on the individual's skill level and experience, some DIY enthusiasts may be able to address the B127B GMC code by following repair guides, but professional assistance is recommended for complex issues.

7. How much does it typically cost to repair the B127B GMC code for the rearview camera input signal circuit?

- The cost of repair can vary depending on the root cause of the issue, but it may involve expenses for replacement parts, labor charges, and diagnostic services from a qualified mechanic or dealership.

8. Are there any preventive measures to avoid encountering the B127B GMC trouble code in the future?

- To prevent the B127B GMC code from recurring, it is advisable to perform regular maintenance checks on the rearview camera system, keep the connections clean and secure, and address any issues promptly.

9. Can extreme weather conditions affect the rearview camera input signal circuit and trigger the B127B GMC code?

- Yes, extreme weather conditions such as heavy rain, snow, or extreme temperatures can potentially damage the rearview camera system components and contribute to triggering the B127B GMC trouble code.

10. How long does it typically take to resolve the B127B GMC code related to the rearview camera input signal circuit?

- The duration of resolving the B127B GMC code can vary based on the complexity of the issue, availability of replacement parts, and the mechanic's workload, but it may take a few hours to a day for repairs to be completed.