Door latch switch
 

Just got my 2003 F250 Superduty running again, she'd been sitting for about 18mo on the ranch where there's lots of dust or rain (depending on the season). I suspect this problem started before the no-start issue... at first the front passenger door would activate the dome light & door ajar dash light when it was closed, both turning off when the door was opened. Now the dome & dash lights are on all the time, no matter the door being open or shut. A little googling told me it's either the latch or the switch at the bottom of the latch. Tomorrow I'll have time to take the switch apart & clean it, but if that doesn't work it'll have to be replaced. So 2 questions.... do I replace the entire latch including the switch, or just the switch? Is this something that I should go Motorcraft on, or is aftermarket ok? The no-start issue was a glow-plug problem, all 8 replaced with Motorcraft because I'd read that aftermarket will likely fail again... and yeah she's a 7.3, no way would I buy a 6.0 :P

Video here: www.youtube.com/watch?v=7eiHvOG8M0w

You just replace the switch.

The door "open" system works by Grounding
When the door is open the switch is closed, so GEM or SJB has a Ground on that wire coming from the latch, and it turns on Dome light, and also Door Ajar Light if key is on

When door is closed switch is open so no ground.

99% of the time the door switch is the problem
Once you unplug the switch(its now open so no Ground), reconnect battery/power and make sure dome light and then Door Ajar light are no longer on
If they are then wire is shorted to Ground somewhere, not a likely issue but better to test it now than have to pull it apart again

Thanks for the video link! What do you think about Motorcraft vs aftermarket specifically on this part? There's a ridiculously huge difference in price.

I weigh the time it takes to change the part and the inconvenience of the part failing.

For Fuel pumps I get Motorcraft, because they are a pain to change and bad "new" pump can strand you, so I bite the bullet and pay the extra.

For a door switch.................I would save the money, really up to you and what your time is worth, bad door switch won't strand you on the side of the road..........well I hope not, lol, so its all about the time it takes to change the switch.

That's some solid logic ;) Nobody local had aftermarket in stock & I wanted to get it done on Sunday, so I wound up going Motorcraft on that one. Thanks for your help!

Your welcome and good work changing it out