Where the 05 chrysler 300 safety switch located?

Check under the dash not far from the steering post. Most cars are in this area.Middle to high area.

If the engine is the hemi it is behind and below the alternator.

the crankshaft sensor location: upper right side of transmission bellhousing, held by one bolt,accessed from under car use jackstands for safety

Could be a bad connection between the battery and starter, or a problem with the neutral safety switch.
Did you take the battery out and have it tested ?

2005 Chrysler 300 Car Stereo Wiring Diagram
Car Radio Battery Constant 12v+ Wire: Gray/Light Green
Car Radio Accessory Switched 12v+ Wire: The radio harness does not provide a switched power source. Run a wire to the fusebox for switched power.
Car Radio Ground Wire: Black/Light Green
Car Radio Illumination Wire: N/A
Car Stereo Dimmer Wire: N/A
Car Stereo Antenna Trigger Wire: N/A
Car Stereo Amp Trigger Wire: N/A
Car Stereo Amplifier Location: N/A
Car Audio Front Speakers Size: N/A
Car Audio Front Speakers Location: N/A
Left Front Speaker Positive Wire (+): Gray/Violet
Left Front Speaker Negative Wire (-): Gray/Yellow
Right Front Speaker Positive Wire (+): Dark Green/Violet
Right Front Speaker Negative Wire (-): Dark Green/Yellow
Car Audio Rear Speakers Size: N/A
Car Audio Rear Speakers Location: N/A
Left Rear Speaker Positive Wire (+): Dark Green/Tan
Left Rear Speaker Negative Wire (-): Dark Green/Gray
Right Rear Speaker Positive Wire (+): Dark Green/Brown
Right Rear Speaker Negative Wire (-): Yellow/Green

See Technical Service Bulletin - 18-003-05 - do not permit the dealer to charge more for diagnostics - just .8 of an hour for reprogramming. - 1 note - ensure your cruise control is working after service as mine did not!

Under the dash, drivers side.

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ITS NOT THE SAFETY SWITCH ON BAKE PEDAL,WENT THRU SAME THING, HUSBAND TOOK IT APART, AND THE SPRING WAS BROKEN. THE SPRING IS PART OF THE BRIGHT PINK SAFETY SWITCH, EVERYONE IS TALKING ABOUT. IT KEEPS PRESSURE ON IT, SO WHEN ITS PRESSED IT RELEASES IT. WE OWN A 2006 CHRYSLER 300..

Safety switch located under the gear stick mechanism inside the car.Needs replacement.