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
When ignition switch is turned to RUN, SDM performs tests to diagnose critical internal malfunctions. Next, SDM measures IGNITION 1 and deployment loop voltages to make sure they are within normal ranges. SDM then proceeds with CURRENT SOURCE diagnostics. DRIVER SIDE LO terminal A3 is grounded through a resistor and driver-side current source connected to DRIVER SIDE HI terminal A2 allows a known amount of current to flow. By monitoring voltage difference between DRIVER SIDE HI and DRIVER SIDE LO, SDM calculates combined resistance of driver-side air bag module, SIR coil, harness wiring circuits 347 and 348 and connector terminal contact.
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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.