AutoCodes – Toyota – U0129 2015 Toyota RAV4

U0129 2015 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 2015 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 332

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 2015 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 2015 Toyota RAV4 - Lost Communication with Brake System Control Module - AutoCodes.com — U0129 2015 Toyota RAV4 Code - Lost Communication with Brake System Control Module

What does this mean?

What are the Possible Causes of the DTC U0129 2015 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 2015 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 2015 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.

Need more information about the U0129 2015 Toyota RAV4 code?

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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 2015 Toyota RAV4 Code

What does OBDII code U0129 mean for a 2015 Toyota RAV4?

OBDII code U0129 indicates that there is a lost communication issue with the Brake System Control Module, meaning the Engine Control Unit (ECU) is unable to communicate with the brake module.

What are the common symptoms of a U0129 code?

Common symptoms include warning lights on the dashboard, such as the ABS or brake warning lights, decreased braking performance, and unresponsive brake system controls.

What could cause a U0129 code in a 2015 Toyota RAV4?

Potential causes include faulty wiring or connectors, a malfunctioning Brake System Control Module, issues with the ECU, or problems with other related modules that affect communication.

How can I diagnose a U0129 code?

To diagnose a U0129 code, use an OBDII scanner to confirm the code, check for any additional codes, inspect wiring and connectors for damage, and test the Brake System Control Module for functionality.

What are some common repairs for a U0129 code?

Common repairs may include repairing or replacing damaged wiring and connectors, replacing the Brake System Control Module, or reprogramming the ECU if necessary.

Can a dead battery cause a U0129 code?

Yes, a dead or weak battery can lead to communication issues between modules, potentially triggering a U0129 code.

Is it safe to drive a 2015 Toyota RAV4 with a U0129 code?

Driving with a U0129 code may not be safe, as it can affect braking performance and overall vehicle safety. It is advisable to have the vehicle diagnosed and repaired as soon as possible.

How can I clear a U0129 code after repairs?

After completing the necessary repairs, you can clear the U0129 code using an OBDII scanner or by disconnecting the vehicleâ€™s battery for a few minutes and then reconnecting it.

Will a U0129 code affect other vehicle systems?

Yes, a U0129 code can affect other systems that rely on communication with the Brake System Control Module, such as the ABS system, potentially leading to further issues.