2012 Sportsman 400/500 and EFI Tractor Service Manual 9923412, Page 277Get this manual
FINAL DRIVE ADC Operation
Engaging Front Gearcase: Active Descent Control (ADC) is controlled by the ECU and will not enable until the following conditions are met: Vehicle speed is below 15 Mph (24Kph) Throttle Position Sensor (TPS) is at idle position The AWD switch is switched to AWDADC' Once the conditions are met for engagement, ADC remains engaged as long as the conditions are metWith the AWD switch set to 2x4', the vehicle drives only the rear wheels (2 wheel drive)When the AWD switch is set to 4x4' the magnetic coils are active, the AWD coil indexes the clutch mechanism so that both front axles will engage when there is loss of rear wheel tractionIn addition to the rear wheel engine braking, the ADC coil provides front wheel engine braking at speeds less than 15 Mph (24Kph) with the TPS at idle positionADC Engagement: When the AWD switch is set to 4x4 ADC', 12 Vdc current is present at the input shaft coil (1)Operation is controlled by the ECU grounding and ungrounding the coilThe coil's magnetic field attracts splined armature plate (2) on the pinion (input) shaft (4)The energized splined armature plate attracts the unsplined eccentric cam (3), which begins to turn with the input shaftThe eccentric cam pushes on the hydraulic pistonpump assembly (5)The pressure created by the pump assembly forces hydraulic fluid through passages to the piston assemblies (6) located in each case halfHydraulic pressure forces the piston assemblies inward to compress the splined clutch packs (7) forming dynamic coupling to each front drive axle, resulting in true all-wheel EBS operation upon decelerationDisengagement: Current to the ADC coil is turned off by the ECU anytime the following conditions are met: Throttle Position Sensor (TPS) moves off idle position The AWD switch is switched to 4x4' or 2x4' Vehicle speed is above 15 Mph (24Kph) Hydraulic pressure stops and the pistons release, disengaging the ADC functionThe vehicle returns to rear wheel drive until the next deceleration