Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC B2278 Power Switch Circuit Malfunction: Description
This DTC is output when 1) a malfunction is detected between the main body ECU and the power switch; or 2) either of the switches inside the power switch is malfunctioning.
HINT:
When the main body ECU is replaced with a new one and the negative (-) battery terminal is connected, the power source mode becomes the IG-ON mode. When the battery is removed and reinstalled, the power source mode that was selected when the battery was removed is restored.
After the main body ECU is replaced, perform the registration procedures for the engine immobilizer system (See REGISTRATION ).
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| B2278 | Communication is abnormal between the main body ECU and power switch or the power switch is defective |
|
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.