So I have this light on since I bought the truck and have no idea where to start? Anyone help out haha.

 

I get that time to time. But my issue is the vsm going out. Maybe yours is just a switch on the door somewherr

 

If like mine, extracab, just spray with wd40 on all actuating parts n levers that the main door hits, on the ectracab part

 

dirty door ajar switch.
open door, and spray penetrating oil down into door latch assembly in door. close/open door about 10-15 times. open door and spray it again, and repeat open/close deal. this should clean the switch.
i usually have to do it once a year

 

Do you have access to AutoEnginuity?

If so, it has an option to monitor the doors. 0 is closed, 1 is open.

Doors 1-4, plus 5 is hatch.

FYI. The hatch sensors can be troublesome. You can pull the switch, remove the wires and twist them together for testing. It has TWO sensors, BOTH must go closed.

Really simple to replace from a junkyard if necessary.

Regular doors, do as mentioned above should get you going. The hatch sensors are the only ones I've known to need replaced and couldn't be lubed-n-fixed