Can't you use the key to open the trunk? The vacuum pump should be on the passenger side corner towards the tail ligt. It's probably covered in a foam housing. Unplug the connecter to the pump and check that it is getting voltage when you lock/unlock the driver door. There are 3 pins connected to 3 wires (brown, blue, and yellow). Brown is ground and the other two are for the lock/unlock circuit. I can't remember which is which. If no voltage, the switch in the driver door might need replacement. Else, you have a leak. Good luck.

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2001 Dodge Ram 2500 Cummins Turbo Diesel - 4x4, auto, 3.54 gears, long bed
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