S15/T15 4WD Jimmy V6-262 4.3L VIN Z (1992)
Four Wheel Drive Indicator Lamp: Description and Operation
The Four-Wheel Drive (4WD) Indicator Assembly provides visual information about the operating mode and gear range at the driveline. Voltage is
supplied to the IGN/GAU Fuse and Indicator Assembly with the Ignition Switch in START or RUN. The circuit is completed through the Selector
Quadrant Switch, which provides a ground path to light various Indicator Assembly Lamps.
With the Selector Quadrant Switch in detent position 1, the "2WHL" Indicator Assembly Lamp is lit.
With the Selector Quadrant Switch in detent position 2, the "4 HIGH* Indictor Assembly Lamp is lit. At this time, the Front Axle Switch is closed and
the Indicator Assembly Front and Rear Axle Display is lit.
With the Selector Quadrant Switch in detent position 4, the "4 LOW" Indicator Lamp is lit. At this time, the Front Axle Switch is closed, and the
Indicator Assembly Front and Rear Axle Display is lit.
A signal is sent to the Rear Wheel Antilock (RWAL) Brake Module and the Four-Wheel Antilock Brake Module (4WAL) whenever the 4WD is
engaged. This signal turns off the RWAL and 4WAL systems to prevent operation during 4WD operation.
VACUUM SYSTEM
When the Four-Wheel Drive shifter is moved to a four-wheel range, a shift mechanism in the transfer case closes the Transfer Case Vacuum Switch.
Closing this switch applies vacuum to the vacuum actuator. The vacuum actuator pulls a cable, which pulls the shift fork in the front axle. This connects
the axle output shaft to the front axle differential to apply torque at the front wheels.
Moving the shifter to the two-wheel range causes the vacuum switch to open to the vent position and the actuator releases the cable to the shift fork in
the front axle. This returns the operation to the two-wheel drive position.
