Differential Electronic Module (DEM) and Active On-Demand Coupling
WARNING: This page is about a different car, the 2006 Mercury Montego, 2006 Ford Freestyle, and 2006 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.
The main role of active on-demand coupling and the differential electronic module (DEM) is to regulate the all wheel drive (AWD) function by distributing torque between the front and rear axles. The system consists of a coupling that combines mechanical, hydraulic and electronic sections. The coupling unit is attached to the rear axle, between the differential gear and the driveshaft. The mechanical and hydraulic sections are driven by the driveshaft. Active on-demand coupling (AOC) has the following characteristics:
- Permanent AWD with electronic control of torque transfer front to rear
- Similar to four wheel drive (4WD) operation
- No driveline wind-up during slow speed maneuvers or parking
The system is not sensitive to size differences between the 4 road tires (when driving with a spare wheel, for example). The system is not sensitive to being towed with one axle raised.