Incorrect... The Vari-Lok differentials use hydraulic pressure to lock up, not electronics.
Quadra-Drive employed the New Venture Gear NV247 transfer case. This two-speed chain-driven transfer case uses a gerotor, a clutch pack coupled to a hydraulic pump, to transfer torque between the front and rear axles. The transfer case contains three modes, 4-All Time, Neutral, and 4-Lo. In 4-All Time, torque is applied to the rear wheels under normal driving conditions. If the rear axle starts spinning at a higher rate than the front axle, hydraulic pressure builds up in the gerotor and causes the clutch pack to progressively transfer torque to the front axle until both axles return to the same speed. Neutral mode is intended for towing the vehicle. In 4-Lo, the front and rear axles are locked together through a 2.72 reduction gear ratio.
In Quadra-Drive, the NV247 transfer case is mated to front and rear axles containing Jeep's Vari-Lok differentials. Vari-Lok differentials also use a gerotor to transfer torque between the two wheels.