On my 00 7.3 master cylinder, there are two sensors- one in the middle on the fender side and another one in the front towards the motor- the one in the front is leaking but parts guy doesn't know what it is-- any ideas

 

Not even the Ford counter guy?
I think it's the cruise control switch that had a recall for starting fires while the truck is sitting in the driveway. Don't quote me on this, I recommend trying a search.

 

Thanks-- finally got someone who knew his stuff- yes it is the cruise switch but he didn't mention anything about starting fires- did hear about some type of recall for my truck on cruise issue but Ford doesn't have serial numbers yet and not allot of details

 

does this also affect the horn??seen other threads that refer to this-- my horn also does not work

 

does this also affect the horn??seen other threads that refer to this-- my horn also does not work but can hear relay toggle

 

The thing to do is to test for 12v at that switch with the ignition turned off. If it's hot then it's on the recall list, if my memory serves me correctly.
On my truck it turns off when I kill the ignition and when I asked at the dealer whether my truck was on that recall list or not, I was informed that my truck was not on the list.