AutoCodes – Scion – B278A Scion

B278A Scion Code - Short to GND in Immobiliser System Power Source Circuit

Quick Answer

When there is a short to GND in the power supply for the Transponder Key Amplifier of the Engine Switch, the Certification ECU (Smart Key ECU Assembly) stores this Diagnostic Trouble Code (DTC). Common causes include Faulty Engine Switch, Engine Switch harness is open or shorted, Engine Switch circuit 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: B278A Scion indicates Short to GND in Immobiliser System Power Source Circuit.
Common causes: Common causes include Faulty Engine Switch, Engine Switch harness is open or shorted, Engine Switch circuit 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 958

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 Jan 16, 2023

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code B278A Scion Description

When there is a short to GND in the power supply for the Transponder Key Amplifier of the Engine Switch, the Certification ECU (Smart Key ECU Assembly) stores this Diagnostic Trouble Code (DTC).

OBDII Code B278A Scion - Short to GND in Immobiliser System Power Source Circuit - AutoCodes.com — B278A Scion Code - Short to GND in Immobiliser System Power Source Circuit

What does this mean?

What are the Possible Causes of the DTC B278A Scion?

Faulty Engine Switch
Engine Switch harness is open or shorted
Engine Switch circuit electrical connection
Faulty Certification ECU (Smart Key ECU Assembly)

How to Fix the DTC B278A Scion?

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 B278A Scion 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 B278A Scion Code

1. What are common symptoms of OBDII code B278A (Short to GND in Immobiliser System Power Source Circuit)?

- Common symptoms include the engine not starting, difficulty starting the vehicle, and the immobilizer light staying illuminated on the dashboard.

2. What can cause the OBDII code B278A to occur in a Scion?

- This code can be triggered by a short to ground in the immobilizer system power source circuit, faulty wiring connections, or a malfunctioning immobilizer system control module.

3. How can I diagnose the issue related to code B278A in my Scion?

- Diagnosing this code often involves checking the wiring harness for shorts or damage, inspecting the immobilizer system components, and using a diagnostic scanner to retrieve specific fault codes.

4. Is it safe to continue driving my Scion with the B278A code present?

- It is not recommended to drive the vehicle with this code active, as it may lead to starting issues or potential immobilization of the vehicle.

5. Can I repair the B278A code in my Scion myself?

- Unless you have experience with automotive electrical systems, it is advisable to seek professional help to diagnose and repair the issue related to this code.

6. How much does it typically cost to repair the B278A code in a Scion?

- The cost of repairing this code can vary depending on the specific cause of the issue, but it may involve replacing wiring harnesses, repairing connections, or replacing the immobilizer system control module.

7. Are there any preventive measures I can take to avoid the B278A code in the future?

- Regularly inspecting the wiring harness for signs of wear or damage, ensuring proper maintenance of the vehicle's electrical system, and avoiding water damage to the immobilizer components can help prevent this code from occurring.

8. Will resetting the OBDII codes make the B278A code go away?

- Resetting the codes may temporarily clear the B278A code, but if the underlying issue is not addressed, it is likely to reappear once the vehicle is driven again.

9. Can a weak car battery cause the B278A code to trigger?

- A weak or failing car battery can potentially cause electrical issues that may lead to the B278A code being triggered, so it is important to ensure the battery is in good condition.

10. Is the B278A code specific to Scion vehicles, or can it occur in other car makes and models?

- While the specific code B278A may be unique to Scion vehicles, similar issues related to the immobilizer system power source circuit can occur in other car makes and models as well.