AutoCodes – Toyota – U1104 2015 Toyota RAV4

U1104 2015 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 2015 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 219

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

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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 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 Driving Support ECU has not been received.

OBDII Code U1104 2015 Toyota RAV4 - Lost Communication with Driving Support ECU - AutoCodes.com — U1104 2015 Toyota RAV4 Code - Lost Communication with Driving Support ECU

What does this mean?

What are the Possible Causes of the DTC U1104 2015 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 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 U1104 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.

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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 2015 Toyota RAV4 Code

1. What does the OBDII code U1104 mean for a 2015 Toyota RAV4?

The code U1104 indicates a communication error with the Driving Support Electronic Control Unit (ECU) in your vehicle.

2. What are the common symptoms of a U1104 code in a 2015 Toyota RAV4?

Common symptoms include the malfunction indicator light (MIL) illuminating on the dashboard, loss of certain driving support features, and potential issues with the vehicle's overall performance.

3. What are some possible causes of a U1104 code in a 2015 Toyota RAV4?

Potential causes of the U1104 code include damaged wiring or connectors, a faulty driving support ECU, software issues, or a communication network problem within the vehicle.

4. How can I diagnose a U1104 code in my 2015 Toyota RAV4?

Diagnosing a U1104 code typically involves using a diagnostic scanner to retrieve the trouble codes, conducting a visual inspection of wiring and connectors, and performing communication tests to identify the specific issue.

5. Is it safe to drive my 2015 Toyota RAV4 with a U1104 code?

While the vehicle may still be operable with a U1104 code, it is recommended to address the issue promptly to prevent potential safety risks and further damage to the driving support system.

6. Can I repair a U1104 code in my 2015 Toyota RAV4 myself?

Depending on your mechanical skills and access to tools, you may be able to address a U1104 code yourself by checking and repairing wiring connections, replacing faulty components, or resetting the ECU.

7. How much does it typically cost to repair a U1104 code in a 2015 Toyota RAV4?

The cost of repairing a U1104 code can vary depending on the specific cause of the issue, the extent of the repairs needed, and whether you choose to address the problem yourself or seek professional assistance.

8. Will resetting the trouble codes clear the U1104 code in my 2015 Toyota RAV4?

Resetting the trouble codes may temporarily clear the U1104 code, but if the underlying issue causing the communication error is not resolved, the code is likely to reappear.

9. Are there any recalls or technical service bulletins related to the U1104 code in a 2015 Toyota RAV4?

It's recommended to check with Toyota dealerships or online resources for any recalls or technical service bulletins related to the U1104 code in your specific vehicle model and year.

10. How can I prevent the U1104 code from occurring in my 2015 Toyota RAV4 in the future?

Regular maintenance, checking for loose or damaged wiring, and addressing any communication issues promptly can help prevent the U1104 code from occurring in your 2015 Toyota RAV4.