AutoCodesScion – B2784 Scion

B2784 Scion Code - Antenna Coil Open / Short

Quick Answer

When an open or short circuit is detected in the Transponder Key Amplifier Coil built into the Engine Switch, the Certification ECU (Smart Key ECU Assembly) stores this Diagnostic Trouble Code (DTC). Common causes include With Smart Key System, Faulty Engine Switch, Engine Switch 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
B2784 Scion indicates Antenna Coil Open / Short.
Common causes
Common causes include With Smart Key System, Faulty Engine Switch, Engine Switch 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 4,562
How popular is this code, among other codes? Low
Table of contents Created and updated by William Orellana on Jan 16, 2023
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Code B2784 Scion Description

When an open or short circuit is detected in the Transponder Key Amplifier Coil built into the Engine Switch, the Certification ECU (Smart Key ECU Assembly) stores this Diagnostic Trouble Code (DTC). This DTC is also stored as a past DTC.
For vehicles without Smart Key System, when an open or short circuit is detected in the antenna coil built into the transponder key coil, the transponder key ECU assembly stores this DTC.
OBDII Code B2784 Scion - Antenna Coil Open / Short - AutoCodes.com
B2784 Scion Code - Antenna Coil Open / Short

What are the Possible Causes of the DTC B2784 Scion?

    With Smart Key System
  • Faulty Engine Switch
  • Engine Switch harness is open or shorted
  • Engine Switch circuit poor electrical connection
  • Faulty Certification ECU (Smart Key ECU Assembly)
    Without Smart Key System
  • Faulty Transponder Key Coil
  • Transponder Key Coil harness is open or shorted
  • Transponder Key Coil circuit poor electrical connection
  • Faulty Transponder Key ECU Assembly

How to Fix the DTC B2784 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 B2784 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 B2784 Scion Code

1. What does the OBDII code B2784 mean on a Scion?

The code B2784 indicates an issue with the antenna coil, which is part of the keyless entry and immobilizer system. It typically means the antenna coil has an open or short circuit.

2. What are the common symptoms of code B2784 in a Scion?

Symptoms may include the engine not starting, the immobilizer warning light staying on, or the inability to use keyless entry features.

3. What causes the B2784 code to appear?

Common causes include a damaged or faulty antenna coil, wiring issues such as frayed or disconnected wires, or a malfunction in the immobilizer system.

4. Can a dead key fob battery trigger the B2784 code?

No, a dead key fob battery typically will not trigger this code, as B2784 specifically relates to the antenna coil's electrical circuit.

5. How do I diagnose the B2784 code on my Scion?

Start by inspecting the antenna coil and its wiring for visible damage or loose connections. Use a multimeter to check for continuity and ensure the circuit is intact.

6. Is it safe to drive with the B2784 code present?

No, it’s not safe because the vehicle may not start or may have issues with the immobilizer system, leaving you stranded.

7. How do I fix the B2784 code on a Scion?

Repairs may involve replacing the antenna coil, fixing damaged wiring, or reprogramming the immobilizer system if necessary.

8. Where is the antenna coil located on a Scion?

The antenna coil is typically located around the ignition key cylinder or near the start button in push-to-start models.

9. How much does it cost to repair the B2784 code on a Scion?

The repair cost can vary, with replacement antenna coils costing $100-$300, plus labor fees if done by a professional.

10. Can I clear the B2784 code without fixing the problem?

Clearing the code without addressing the underlying issue will only temporarily remove the error, and the code is likely to return.

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