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C129D Buick Code - Brake Pedal Position Sensor 4 Circuit Low Input

Quick Answer

The Electronic Brake Control Module (EBCM) uses inputs from the electronic brake control brake pedal position sensor to determine when the brake is applied and how much force is used. Common causes include Faulty Brake Pedal Position Sensor, Brake Pedal Position Sensor harness is open or shorted, Brake Pedal Position Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: C129D Buick indicates Brake Pedal Position Sensor 4 Circuit Low Input.
Common causes: Common causes include Faulty Brake Pedal Position Sensor, Brake Pedal Position Sensor harness is open or shorted, Brake Pedal Position Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 701

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 04, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code C129D Buick Description

The Electronic Brake Control Module (EBCM) uses inputs from the electronic brake control brake pedal position sensor to determine when the brake is applied and how much force is used. The electronic brake control module monitors when the driver's foot is on the brake and locks the offset. The offset is locked when 3 out of the 4 inputs indicate the brake pedal is applied. The 4 inputs are brake pedal travel 1, brake pedal travel 2, master cylinder pressure sensor, and the brake pedal position sensor. These inputs are used to determine the driver's braking intent which is used to the control amount of pressure applied to the wheels.

OBDII Code C129D Buick - Brake Pedal Position Sensor 4 Circuit Low Input - AutoCodes.com — C129D Buick Code - Brake Pedal Position Sensor 4 Circuit Low Input

What does this mean?

What are the Possible Causes of the DTC C129D Buick?

Faulty Brake Pedal Position Sensor
Brake Pedal Position Sensor harness is open or shorted
Brake Pedal Position Sensor circuit poor electrical connection
Faulty Electronic Brake Control Module (EBCM)

How to Fix the DTC C129D 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 is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the C129D 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 C129D Buick Code

1. What are the common symptoms of OBDII code C129D in a Buick related to the Brake Pedal Position Sensor 4 Circuit Low Input?

The common symptoms include issues with the brake lights, cruise control not working properly, and the vehicle going into limp mode.

2. What are the possible causes of OBDII code C129D in a Buick indicating a Brake Pedal Position Sensor 4 Circuit Low Input?

Possible causes include a faulty brake pedal position sensor, damaged wiring or connectors in the sensor circuit, or a malfunction in the brake control module.

3. How can I diagnose the source of OBDII code C129D in a Buick pointing to the Brake Pedal Position Sensor 4 Circuit Low Input?

You can diagnose the issue by checking the brake pedal position sensor for proper operation, inspecting the wiring and connectors for any damage, and using a scan tool to read the sensor data.

4. Can I still drive my Buick with OBDII code C129D indicating a Brake Pedal Position Sensor 4 Circuit Low Input?

It is not recommended to drive the vehicle with this code, as it can affect the proper functioning of the brake system and other safety features.

5. How can I repair OBDII code C129D in a Buick related to the Brake Pedal Position Sensor 4 Circuit Low Input?

Repairing the issue may involve replacing the brake pedal position sensor, repairing any damaged wiring or connectors, or reprogramming the brake control module.

6. Will resetting the OBDII code C129D in a Buick fix the issue related to the Brake Pedal Position Sensor 4 Circuit Low Input?

Simply clearing the code may temporarily remove the warning light, but the underlying issue causing the code will persist until properly diagnosed and repaired.

7. Is it possible to prevent OBDII code C129D in a Buick indicating a Brake Pedal Position Sensor 4 Circuit Low Input?

Regular maintenance and inspections of the brake system, including the pedal position sensor, can help prevent this code from appearing.

8. What is the importance of the Brake Pedal Position Sensor in a Buick's brake system?

The Brake Pedal Position Sensor helps the vehicle's computer system determine the position of the brake pedal, which is crucial for the proper operation of various safety features and systems.

9. Can a DIY enthusiast replace the Brake Pedal Position Sensor in a Buick to address OBDII code C129D?

Replacing the sensor may require some technical knowledge and the right tools, so it is recommended to consult a professional mechanic for proper diagnosis and repair.

10. How long does it typically take to repair OBDII code C129D in a Buick related to the Brake Pedal Position Sensor 4 Circuit Low Input?

The repair time can vary depending on the exact cause of the issue, but it may take anywhere from an hour to a few hours to diagnose and repair the problem effectively.