Engagement of Chrysler's Dodge Ram four-wheel drive system is accomplished through a shift lever, or through push-buttons, depending on model. Shifting into four-wheel drive can be problematic because shifts require certain speeds to be maintained. The system also won't work under some conditions because of the complexity of the multiple drive-shafts functioning together.
Verify that your tires are of equal size, type and circumference if shifting into 4-wheel drive is difficult. Replace any tires that don't match in order to use 4-wheel drive and avoid transfer case damage.
Stop spinning the wheels before trying to shift into four-wheel drive. The system can't handle the front and rear drive shafts moving at different speeds because, unlike regular gears, there's no synchronization. The speeds have to be equal for the shift to work.
Check for uneven tire pressure, tire wear or excessive loading if you continue to have problems engaging four-wheel drive. Weight limits and tire pressure are specified on a label on the driver's side door. Cold temperature can be particularly problematic and temperatures below freezing can delay the shift markedly. You may need to stop to shift into four-wheel drive in particularly cold temperatures.
Shift from "2H" into "4H," and back again at speeds below 55 mph. Remember that cold weather can reduce this speed considerably. Drop your shift speed significantly if the temperature is below freezing. Shift into "4LO" out of a running gear, and at speeds below or at 3 mph, and don't pause in the transfer case's "Neutral" position.
