AutoCodes – Toyota – B278C Toyota

B278C Toyota Code - Lost Communication With Power Source Control

Quick Answer

This Diagnostic Trouble Code (DTC) is stored when Local Interconnect Network (LIN) communication between the Certification ECU (Smart Key ECU Assembly) and Power Management Control ECU stops for 10 seconds or more. Common causes include Faulty Power Management Control ECU, Power Management Control ECU harness is open or shorted, Power Management Control ECU 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: B278C Toyota indicates Lost Communication With Power Source Control.
Common causes: Common causes include Faulty Power Management Control ECU, Power Management Control ECU harness is open or shorted, Power Management Control ECU 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 4,939

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 Jan 27, 2020

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B278C Toyota Description

OBDII Code B278C Toyota - Lost Communication With Power Source Control - AutoCodes.com — B278C Toyota Code - Lost Communication With Power Source Control

What does this mean?

What are the Possible Causes of the DTC B278C Toyota?

Faulty Power Management Control ECU
Power Management Control ECU harness is open or shorted
Power Management Control ECU circuit poor electrical connection
Faulty Certification ECU (Smart Key ECU Assembly)

How to Fix the DTC B278C Toyota?

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 B278C Toyota 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 B278C Toyota Code

1. What are the common symptoms of OBDII code B278C (Lost Communication With Power Source Control) in a Toyota?

The common symptoms include loss of power steering assist, illuminated dashboard warning lights, and intermittent or complete power steering failure.

2. What are the possible causes of OBDII code B278C in a Toyota?

Possible causes include a faulty power steering control module, wiring or connection issues, blown fuses, or a malfunctioning power steering motor.

3. How can I diagnose the source of the communication failure with the power source control in my Toyota?

Performing a thorough inspection of the power steering system, checking for loose or damaged wiring, and using a diagnostic scan tool to retrieve codes and data can help pinpoint the issue.

4. Can OBDII code B278C be triggered by a dead or weak battery in a Toyota?

Yes, a dead or weak battery can sometimes trigger this code due to inadequate power supply to the power steering control module.

5. What are some repair tips for addressing OBDII code B278C in a Toyota?

Inspect and repair any damaged wiring or connections, replace blown fuses, ensure the battery is in good condition, and consider resetting the power steering system after making repairs.

6. Is it safe to continue driving my Toyota with the B278C code present?

It is not recommended to drive the vehicle with this code present, as it can lead to sudden loss of power steering assist, making the vehicle difficult to steer and potentially unsafe to drive.

7. Can a DIY enthusiast without advanced automotive knowledge fix the B278C code in a Toyota?

While some basic troubleshooting steps can be taken, diagnosing and repairing issues related to this code may require specialized tools and expertise, so seeking professional help is advised.

8. How much does it typically cost to repair OBDII code B278C in a Toyota?

The cost of repairs can vary depending on the exact cause of the issue, but it may range from a few hundred to over a thousand dollars, including parts and labor.

9. Will resetting the OBDII code B278C in a Toyota make the problem go away permanently?

Simply resetting the code without addressing the underlying issue will not fix the problem permanently. It is important to diagnose and repair the root cause to prevent the code from reappearing.

10. Can extreme weather conditions or rough road conditions trigger the B278C code in a Toyota?

Extreme weather conditions or rough road conditions can potentially exacerbate existing issues in the power steering system, leading to the triggering of the B278C code.