AutoCodes – Toyota – U1104 2014 Toyota RAV4

U1104 2014 Toyota RAV4 Code - Lost Communication with Driving Support ECU

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 Driving Support ECU, Driving Support ECU 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: U1104 2014 Toyota RAV4 indicates Lost Communication with Driving Support ECU.
Common causes: Common causes include Faulty Controller Area Network (CAN) Communication System, Faulty Driving Support ECU, Driving Support ECU 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 213

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 27, 2023

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code U1104 2014 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 Driving Support ECU has not been received.

OBDII Code U1104 2014 Toyota RAV4 - Lost Communication with Driving Support ECU - AutoCodes.com — U1104 2014 Toyota RAV4 Code - Lost Communication with Driving Support ECU

What does this mean?

What are the Possible Causes of the DTC U1104 2014 Toyota RAV4?

Faulty Controller Area Network (CAN) Communication System
Faulty Driving Support ECU
Driving Support ECU harness is open or shorted
Driving Support ECU circuit poor electrical connection

How to Fix the DTC U1104 2014 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 U1104 2014 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 U1104 2014 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 U1104 2014 Toyota RAV4 Code

1. What does the OBDII code U1104 in a 2014 Toyota RAV4 mean?

- The U1104 code indicates a "Lost Communication with Driving Support ECU" error in the vehicle's onboard diagnostics system.

2. What are the common symptoms of the U1104 code in a 2014 Toyota RAV4?

- Common symptoms include issues with the vehicle's driving support systems, such as adaptive cruise control, lane keeping assist, or collision warning systems not functioning properly.

3. What are the possible causes of the U1104 code in a 2014 Toyota RAV4?

- The U1104 code can be triggered by issues such as a faulty driving support ECU, damaged wiring or connectors, a software malfunction, or a communication network problem.

4. How can I diagnose the U1104 code in my 2014 Toyota RAV4?

- Diagnosing the U1104 code typically involves using a diagnostic scan tool to retrieve the trouble codes, checking the driving support ECU for faults, inspecting the wiring and connectors, and performing a network communication test.

5. Can I still drive my 2014 Toyota RAV4 with the U1104 code present?

- It is not recommended to drive the vehicle with the U1104 code active, as it may affect the proper functioning of important driving support systems, compromising safety.

6. How can I repair the U1104 code in my 2014 Toyota RAV4?

- Repairing the U1104 code may involve fixing any wiring or connector issues, replacing a faulty driving support ECU, updating software if necessary, or addressing any communication network problems.

7. Can the U1104 code in a 2014 Toyota RAV4 be reset without fixing the underlying issue?

- While you can clear the U1104 code using a diagnostic scan tool, it is crucial to address the root cause of the problem to prevent the code from reoccurring.

8. Is the U1104 code common in 2014 Toyota RAV4 vehicles?

- The U1104 code is not extremely common, but it can occur in 2014 Toyota RAV4 models due to various factors affecting the driving support ECU and communication systems.

9. Will fixing the U1104 code require professional help or can it be done at home?

- Depending on the underlying issue causing the U1104 code, repairs may require professional assistance, especially when dealing with complex electronic components and system diagnostics.

10. How can I prevent the U1104 code from appearing in my 2014 Toyota RAV4 in the future?

- Regular maintenance, checking for wiring issues, ensuring proper connections, and addressing any warning signs promptly can help prevent the U1104 code from reoccurring in the future.