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.
Circuit Description
Electronic Frontal Sensor (EFS) uses a unidirectional 2-wire circuit. EFS modulates current on the interface to send identification, State Of Health (SOH) and deployment commands to Sensing and Diagnostic Module (SDM). SDM provides power and ground to EFS. When ignition is turned on and power from SDM is detected by EFS, EFS performs internal diagnostics, then sends an identification message to EFS. SDM receives identification message within 5 seconds of power being turned on and determines if message is valid. EFS continually communicates a status message to SDM. When a fault is detected, SDM resets EFS twice by removing and reapplying power to SIS. If fault is still present, SDM will set applicable DTC.
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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.