Four-Wheel Drive Basics. A 4WD system sends torque to all four of a vehicle’s wheels. This system is typically found in trucks and body-on-frame SUVs. On the other hand, all-wheel drive (AWD) is another technology that shares many similarities but typically uses a center differential to convey the engine’s torque between the two axles while There are two shift motors. 1. Shift motor 1:. 2wd, auto and 4hi to disengage/engage chain drive to front shaft. There is no issue with this operation. 2. Shift motor 2:. To engage/disengage 4lo planetary gear reduction. 4lo issue could be seized slider due to wear or bad shift motor. 1.c) The best system is: manual TC with lever, locking hubs and lockable front and rear diff. 2) they change/repair it. 2.a) a 2018 Ram is not a car you need diff locks, you need diff locks if you wanna do hardcore offroad, and a 4th gen Ram is not the right car for that. 2.b) I don't know, but you don't need it. For all wheel drive to work when reversing, a vacuum-actuated "throttle control element" is installed on the differential case. This device locks the freewheel mechanism when in reverse gear. The freewheel mechanism unlocks when the gear shift lever is pushed to the right pass the 3rd gear. AUTOMATIC TRANSFER CASES. The last category is a combination of 4WD and On Demand AWD. These transfer cases have a 2HI, Auto-4WD, 4HI, 4LO and Neutral position and would fall in the general 4WD category. This transfer case has the operating characteristics of both an On Demand AWD and a Part-Time 4WD system depending on the mode selected. Auto 4WD is full-time 4WD which does send varying amounts of power to the front axle 100% of the time. It does not run in pure 2WD mode until it detects slippage and it is safe to run auto 4WD 24/7/365 without worry, it's the same full-time 4WD transfer-case used in various Jeep Grand Cherokees only ours is a beefier version. Four-wheel-drive auto is the default four-wheel-drive mode when sport mode is activated. When to use it : If you’re driving on a road where performance is key, engage sport mode. It tightens up steering, enhances driver feedback, and increases responsiveness to steering wheel inputs to give you a feistier and more fiery drive. What is 4WD And How Does It Work? Most cars have traditionally been two-wheel drive, meaning the engine propels two of the wheels and the other two are along for the ride. Usually, the rear wheels receive engine power. Historically, 4WD was mainly used for military vehicles. After World War II, Dodge began offering 4WD as a feature on trucks. Part-time systems operate in two-wheel-drive mode until the driver — or an onboard computer that monitors traction — decides that it's time for all four wheels to share the work. Full-time 4WD Engaging the 4×4 on a GMC Sierra is easy. There’s a knob on the left side of the driver’s controls that allows choosing between Two-High (2H), Four-High (4H), or Four-Low (4L). Some GMC Sierras come with the Automatic 4H, which sends torque to the front axle when it senses less traction. The situations in which you select each mode vary. etzqQ.