mystery vacume pump

[chainsaw]

Does anyone know what the purpose of the small vacume pump located above the fuse box in the engine compartment? It's between the battery and firewall. When I shut the engine off with the key in the run position the pump keeps running. I disconnected the vacume line and put my finger over the vacume port and the pump shut off. Everything on the truck seems to still work. My truck is a 08 F250 6.4L CC 4x4. Thanks.

[chainsaw]

The part number on the pump is 7c34-2a451-bb. When I Google the part number, all I see is that it's a vacume pump.

[04hdfatboy]

I believe its a vaccum pump for the automatic hubs. If it keeps running you have a leak somewhere.

[chainsaw]

Thanks for the info 04hdfatboy. Does anyone know where they typically leak?

[04hdfatboy]

usually its the hose that runs toward the front of the truck. They tend to crack.

[countryraised]

Also the seals inside the hubs will go bad. Those get a little pricey.

[chainsaw]

Thanks everyone for your help so far. The vacume line between the pump the T junction was broken. The vacume line that runs on top of the radiator shroud to a relay on the passenger side does not leak but the line that runs under the degaus bottle does have a leak. Does anyone know where it goes? Is there a vacume line schmatic anywhere for a 08? Are any of the vacume lines availalbe from the dealer?