Control Module: Description and Operation

OPERATION
The Electronic 4 Wheel Drive Module monitors the Front and Rear Axle Speed Sensors for tire slippage. If the slippage is low, the front and rear axle speeds will be very close, and the Electronic 4 Wheel Drive Module will not engage the Transfer Case Clutch Solenoid. This allows the front and rear axles to rotate independently. If the Electronic 4 Wheel Drive Module senses a significant difference in axle speeds, it will engage the Transfer Case Clutch Solenoid. The front and rear axles, locked by the Transfer Case Clutch, rotate together to allow the wheels with the greatest traction to pull the vehicle. The Transfer Case Clutch is engaged for about 3.3 seconds, and is then disengaged. The clutch will re-engage after about 0.5 seconds if wheel slippage continues.

The Electronic 4 Wheel Drive Module also monitors the Brake Switch and the Backup/Neutral Safety Switch. If the vehicle is in NEUTRAL or the brake is on, the Transfer Case Clutch will not engage or will disengage immediately. The Electronic 4 Wheel Drive Module will not engage the Transfer Case Clutch above 35 mph.