2007-2014 Expeditions all use the BorgWarner Torque on Demand (BW TOD) tranfer case system. ‘07-‘14 Expeditions TOD transfer case uses a specialized microprocessor (computer) in the transfer case that senses and can predict slippage before it occurs based on conditions monitored every millisecond in 4A mode. In 4A torque is variable and sent where needed via the cases brain. When you put it into 4H or 4L the transfer case computer locks it up 50/50 torque split front and rear with high or low range and no longer varies output. You have manually taken over its job and told it to lock everything up (needed in mud or rock crawling). This is good for severe conditions where slip can occur but on dry asphalt will result in binding of the driveline.
