Tahoe 4WD V8-393 6.5L DSL Turbo VIN S (1995)
Four Wheel Drive Indicator Lamp: Initial Inspection and Diagnostic Overview
Circuit Operation - Four-Wheel Drive Indicator
When the Ignition Switch is in RUN and the four-wheel drive control lever is engaged, the transfer case switch closes and battery voltage is supplied
across the front axle actuator. The front axle actuator energizes and the four-wheel drive gears are meshed. This meshing action of the four-wheel drive
gears closes the front axle switch, and battery voltage is supplied through CKT 1695 across the four-wheel drive indicator lighting the bulb.
Battery voltage is also supplied through the front axle switch contacts and CKT 1695 to the rear-wheel or four-wheel antilock brake module. This will
modify the antilock braking system operation in 4WD mode.
A transfer case relay is used on one-ton vehicles with four-wheel drive. This relay is de-energized when the vehicle is in 4WD mode. From the transfer
case relay, voltage is supplied to the transfer case synchronizer until 4WD mode is selected.
Troubleshooting Hints - Four-Wheel Drive Indicator
1. Make sure all mechanical components are operative before diagnosing electrical portion of four-wheel drive system.
2. To determine whether vehicle is in two-wheel drive or four-wheel drive, lift it up so wheels can spin freely.
3. Check to see that 4WD and ILLUM fuses are not blown. If blown, locate and repair source of overload and replace fuse.
4. While performing the following diagnostic procedures, Ignition Switch must be in RUN and 4WD Control Lever must be in 4WD ENGAGED
position.
