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Supplemental Inflatable Restraints. AIRBAGS. Air bag purpose. To slow down deceleration of occupant Side impacts cushions occupant. Basic air bag operation. When control module detects collision electrical signal is sent to squib
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Air bag purpose • To slow down deceleration of occupant • Side impacts cushions occupant
Basic air bag operation • When control module detects collision electrical signal is sent to squib • Squib ignites generant which will fill bag with nitrogen in about .03 of a second • Air bag will deploy at 200-240 mph • Front bags only deploy in frontal collisions at 25mph approx.. and up
Sensors • Most systems use minimum of 2 sensors • Sensors will have different internal operation • Module will wait to see 2 sensors activate before deployment • Sends electrical signal to module • Will have resistor wired in parallel for diagnostics
Clock (coil) spring • Drivers bag must be hard wired to system but allow for steering wheel rotation • Coil will be under steering wheel • Coil must be centered when column or coil is removed
Knee bolster • Keeps occupant from sliding down under bag • Gives a stopping point for knees • Mandatory with air bag system • Must be in place and tight
Airbag system service • Must be careful with any stray voltage • Airbags will deploy with as little as 3volts - static on your body can be enough to deploy bag • Modules have LARGE capacitors which may need to be discharged • Most harnesses will have shorting clips on airbag wires
Airbag service • Most bags have core charges • Old bags MUST be deployed before shipping (federal laws) • If bags have deployed, normally ALL sensors must be replaced • NEVER, NEVER, NEVER set a live airbag face down on a bench
Airbag diagnostics • Will have warning lamp • If illuminated, system is inop • Systems are self-diagnostic • Most are now scan-able • Others use flash codes • Use basic general electrical diagnostic skills