1994-2002 Dodge 4×4 trucks with the front Dana 60 use a vacuum actuated CAD: center axle disconnect. The system relies on a gear driven vacuum pump off the Cummins motor and plastic tubing leading to the external diaphragm and actuator in the passenger side axle tube, next to the low pinion differential. Inside the CAD assembly is a shift fork that slides a splined collar to engage and disengage the 2 inner axle shafts.
For a truck with cracked or leaking vacuum lines under the hood, the CAD does not engage (incidentally along with related HVAC mode selector), which then prevents the powertrain from reaching the front axle. Also, the open vacuum system will indicate an erroneous 4×4 engagement on the dashboard even with the transfer case in 2wd.
To resolve, added a 4x4Posi-Lok manual cable to engage the shift fork in the CAD housing. The benefit is firstly the manual actuation independent of the vacuum system, and secondly the ability to manually disengage even in 4×4 low range, to run 2wd in low range (similar to running a manual locking front hub axle unlocked in 4×4 low range).
Installation requires routing the thick actuator cable through the firewall and down to the axle housing. The diaphragm and factory CAD cover is eliminated in place of a new cover to reuse the fork and accept the push-pull cable, which then mounts to a bracket in the cockpit below the dash. Also took the opportunity to service and change front differential fluid.