Yes, they are referring to the Inertia switch, its a switch that will "pop" open in an accident, sudden stop, a change in "inertia"
It prevents electric fuel pump from continuing to run and possibly feed fuel to a fire from a broken fuel line
Its not an on/off type switch, like to prevent theft
Yes, usually located in passenger side of cab behind glove box on firewall or behind pasenger side kick panel
Just a small black box with 2 or 3 wires, and a red button that will "pop" up if its tripped/opened
Once these are tripped one time they can be reset BUT...........they will often trip much easier after that, so going off a curb or even slamming a door can cause them to trip again
With the advent of electric fuel pumps there have been several types of "cutoff" switches used, because of the danger of a pump continuing to run in an accident or roll over, mechanical pumps didn't have this issue
On carb engines an oil pressure switch was often used, fuel pump relay wouldn't send power to fuel pump until engine was running, had oil pressure, and would cut power if engine stopped
With fuel injection you can't do that because there is no float bowl for startup
So computer has a 2 second rule
It only activates fuel pump relay for 2 seconds if RPMs are under 400
So key ON gets 2 seconds of fuel pump power, then it won't be power again until engine gets above 400rpms, or unless you reboot computer, key off and on again
If engine should stall while driving, an accident or rollover, then fuel pump is shut off when RPMs drop below 400
Inertia switch is a backup cutoff switch, for either of the above primary cutoff systems
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