What are the sensors called that are underneath the hood on the passenger side firewall called? They're causing my service 4x4 light to come on. I tap them and the light goes off. Probably just dirty contacts.

 

I don't remember what year the solenoid moved, but the 4x4 solenoid(s) used to be mounted on the right hand firewall.
If your doesn't have a rain hood cover the solenoids, it's likely they will need replaced or perhaps as you mention, cleaning the contacts.
Ford came out with a Rainhood at some point in life, I don't know the history well enough to know when any of that happened.

If what I am describing is what you are as well, they are solenoids, not sensors. The solenoid open/closes vacuum supply to the wheels to allow the hubs to lock up.
If you disconnect the electrical, the hubs will remain locked, which is okay to drive if necessary, it is not actually in 4x4 mode by doing that.

 

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After further inspection I tapped on the ecm, not the iwe solenoid. I'm going to further my diagnosis and see what's happening. Maybe it was a coincidence that the check 4x4 light went off when I tapped on the ecm plugs.

 

The ol Fonzy method 😀, let us know what you find.

 

 

I **** you not my friends, I fixed half of all the issues I ever had with the crown vic patrol cars over the years by tapping various areas of the car....EYYYYY.....especially the wiper motors and the blower motors!

 

Yup, seems a lot of older vehicles suffer by their plug connections, just unplugging and re-plugging them helps, best if you add a little dielectric grease whilst you're in there though.