In 4WD equipped vehicles, the transfer case, located at the rear of the transmission, is responsible for transferring engine torque to the front and rear wheels.

The transfer case contains an input gear, countershaft and counter gear, rear output shaft, low output gear and a front output shaft, for front drive, connected and driven by a drive chain.

The transfer case gearshift control lever can be placed in four positions:

The case has an oil gallery and a plate at the synchronizer to provide proper lubrication under normal and harsh driving conditions. The front drive shift fork mechanism has an auxiliary spring to ensure a smooth shift from 4H to 2H.

You can shift from 2H to 4H or from 4H to 2H at any speed less than 100 kph (60 mph) and with the front wheels straight ahead. This is accomplished by a synchronizer installed to the front drive clutch. The front axle will engage faster if you take your foot off the accelerator pedal for a few seconds as you shift.

In 2WD equipped vehicles, the transfer case, located at the rear of the transmission, is responsible for transferring engine torque to the rear wheels. This transfer case is different from that of the 4WD vehicles. It is not equipped with a gearshift control lever for 4H, 4L, 2H, and N positions. This transfer case contains an input gear, countershaft and countergear, rear output shaft and low output gear.

The powertrain control module (PCM) and the front drive axle actuator pump are the main components of the four wheel drive engagement system. The pump is controlled by the PCM. The pump compresses air to engage the front axle. When the transfer case is in four wheel drive (4H or 4L), the four wheel drive switch closes providing a ground signal to the PCM. The PCM actuates the pump which pressurizes the actuator in the front axle. This pressure engages the axle hub which connects the front drive shaft to the axle shafts, allowing the transmission/transfer case to turn the front wheels. The PCM will not operate the pump for more than 10 seconds in order to protect it. The PCM also provides a ground for the 4WD indicator in the instrument cluster. The indicator is provided ignition voltage through the IG fuse. With power and ground supplied, the indicator illuminates.

When the transfer case is in 4L (with auto trans), the four wheel drive low switch provides a ground signal to the PCM. The PCM will not engage the torque converter clutch while this signal is present.

When the transfer case is returned to the two wheel drive mode, the release valve in the pump opens and releases the pressure in the actuator. Without pressure, the hub disengages. The PCM also removes the ground to the 4WD indicator which causes the indicator to turn off.