Transfer Case -Electronic Shift on the Fly (ESOF) Features

A rotary switch allows the vehicle operator to choose between 2WD, 4H, and 4L modes of 4x4 operation.

The Generic Electronic Module (GEM) controls the operation of the 4x4 system.

The Output Shaft Speed (OSS), mounted in the rear of the transfer case, informs the GEM of the vehicle speed.

The shift motor sense plate, an integral part of the electronic shift motor, informs the GEM to the positions of the transfer case (go to Table 4).

The transmission range sensor is located on the LH side of the transmission; this sensor informs the GEM when the transmission is in the NEUTRAL position.

The electronic shift motor, mounted externally at the rear of the transfer case, drives a rotary cam which moves the mode fork and range fork within the transfer case to select between the 2WD, 4H, and 4L positions.

The 4x4/4x2 vacuum solenoids are attached to the upper RH side of the engine compartment, and alternately route vacuum to the vacuum motor which engages/disengages the center axle disconnect collar in the front axle assembly.

The 4x4 shift motor relay is a module containing two relays. Under the control of the GEM, the 4x4 shift motor relay shifts the transfer case shift motor between the 2WD, 4H, and 4L modes.

The transfer case clutch relay is an electromechanical relay used to activate the transfer case clutch within the transfer case.