AutoCodes – Toyota – U0129 2018 Toyota RAV4

U0129 2018 Toyota RAV4 Code - Lost Communication with Brake System Control Module

Quick Answer

The Controller Area Network (CAN) is a standard bus system in vehicles that enables the connection of automotive devices without the need for a host computer. Common causes include Faulty Controller Area Network (CAN) Communication System, Faulty Brake System Control Module, Brake System Control Module harness is open or shorted. 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: U0129 2018 Toyota RAV4 indicates Lost Communication with Brake System Control Module.
Common causes: Common causes include Faulty Controller Area Network (CAN) Communication System, Faulty Brake System Control Module, Brake System Control Module harness is open or shorted.
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 3,571

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 Mar 26, 2023

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code U0129 2018 Toyota RAV4 Description

The Controller Area Network (CAN) is a standard bus system in vehicles that enables the connection of automotive devices without the need for a host computer. The exchange of operating information and commands among devices is facilitated by pre-programmed information about the required message exchange on the serial data circuits. Communication is carried out using two dedicated wires, known as CAN high and CAN low, with both lines carrying 2.5V when the CAN bus is in idle mode. During the transmission of data bits, the CAN high line increases to 3.75V while the CAN low drops to 1.25V, creating a 2.5V differential between the lines. Since communication relies on a voltage differential between the two bus lines, the CAN bus is NOT sensitive to inductive spikes, electrical fields, or other noise. The Diagnostic Trouble Code (DTC) sets when a periodic message from the Brake System Control Module has not been received.

OBDII Code U0129 2018 Toyota RAV4 - Lost Communication with Brake System Control Module - AutoCodes.com — U0129 2018 Toyota RAV4 Code - Lost Communication with Brake System Control Module

What does this mean?

What are the Possible Causes of the DTC U0129 2018 Toyota RAV4?

Faulty Controller Area Network (CAN) Communication System
Faulty Brake System Control Module
Brake System Control Module harness is open or shorted
Brake System Control Module circuit poor electrical connection

How to Fix the DTC U0129 2018 Toyota RAV4?

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

When there are problems with the way different systems in a vehicle communicate with each other using a technology called Controller Area Network (CAN) communication, Diagnostic Trouble Codes (DTC) are displayed. These codes can be caused by issues with the main bus or branch of the communication network, or with the Electronic Control Units (ECUs) and sensors that make up the different systems. If you see code for both the CAN communication problems and internal or power source problems at the same time, you should focus on fixing the internal or power source problems first.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the U0129 2018 Toyota RAV4 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 U0129 2018 Toyota RAV4 Code

1. What are the common symptoms of OBDII code U0129 in a 2018 Toyota RAV4?

The common symptoms include the ABS warning light being illuminated on the dashboard, loss of communication with the brake system control module, and potential issues with the brake system functionality.

2. What are the possible causes of the U0129 code in a 2018 Toyota RAV4?

The U0129 code in a 2018 Toyota RAV4 is typically caused by a faulty brake system control module, damaged wiring or connectors related to the brake system, or issues with the vehicle's electronic control unit (ECU).

3. How can I diagnose the U0129 code in my 2018 Toyota RAV4?

Diagnosing the U0129 code involves using a professional OBDII scanner to read the code and identify the specific communication issue with the brake system control module. Additionally, inspecting the wiring and connectors for any visible damage is recommended.

4. Can I still drive my 2018 Toyota RAV4 with the U0129 code present?

It is not recommended to drive your 2018 Toyota RAV4 with the U0129 code present, as it indicates a potential communication failure with the brake system control module, which can compromise the vehicle's safety and braking performance.

5. How can I repair the U0129 code in my 2018 Toyota RAV4?

Repairing the U0129 code involves addressing the root cause of the communication failure, which may include replacing the brake system control module, repairing damaged wiring or connectors, or reprogramming the vehicle's ECU to establish communication with the brake system.

6. Is it safe to reset the U0129 code in my 2018 Toyota RAV4 with a diagnostic tool?

While resetting the code may temporarily clear the warning light, it is essential to address the underlying issue causing the U0129 code to prevent potential safety hazards and ensure proper functioning of the brake system.

7. How much does it typically cost to repair the U0129 code in a 2018 Toyota RAV4?

The cost of repairing the U0129 code in a 2018 Toyota RAV4 can vary depending on the specific cause of the issue, but it may range from $200 to $800, including parts and labor.

8. Are there any preventive measures to avoid the U0129 code in a 2018 Toyota RAV4?

Regular maintenance checks, including inspecting the brake system components and wiring for any signs of wear or damage, can help prevent the occurrence of the U0129 code in a 2018 Toyota RAV4.

9. Can a DIY enthusiast fix the U0129 code in a 2018 Toyota RAV4?

While some basic troubleshooting steps can be performed by a DIY enthusiast, diagnosing and repairing the U0129 code may require specialized tools and expertise, so it is recommended to consult a professional mechanic for accurate diagnosis and repair.

10. Will the U0129 code in a 2018 Toyota RAV4 affect the vehicle's overall performance?

The U0129 code itself may not directly impact the vehicle's overall performance, but it indicates a potential issue with the brake system control module, which can affect the vehicle's safety and braking functionality if not addressed promptly.