You may know this or not but pull up the carpets and look for the vacuum junctions for each door under the plastic guard on the floor. You can then disconect each door by itself and check each vacuum element without pulling apart the door. Generally with the later door lock vac pulls, the boot goes bad where the rod comes out of the vac element. I believe it is on the side that is the "unlock". An external vacuum source is extreamly handy to trouble shoot this problem. I use my electric A/C vac pump and plumbed up a gauge and valve to evacuate the line, close the valve and watch the gauge. Be sure to check BOTH lines coming from each door except the drivers door. The drivers door doesn't have a vacuum element in it, only the vacuum switch valve.

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My Truck.. 2007 DODGE, 5.9 Cummins, 6spd stick, 4X4. My car..1977 240D, OTHER WHEELS...1955 VW Oval window bug, European Delivery (Holland) with a 1700cc, 2 barrel, Porsche drum brakes. 1939 WILLYS Pick-up. 1967 Triumph 200cc Tiger Cub. 1976 Honda 550F 4cyl Motor Cycle.