Wrangler 4WD V6-3.8L (2009)
Four Wheel Drive Indicator Lamp: Description and Operation
4WD Indicator - Operation
OPERATION
The four-wheel drive indicator gives an indication to the vehicle operator when a four-wheel drive (4WD) mode of the transfer case is selected. This
indicator is controlled either by the instrument cluster circuit board (domestic market vehicles) or by a transistor on the circuit board (export market
vehicles) based upon cluster programming and electronic messages received by the cluster from the Totally Integrated Power Module (TIPM) over the
Controller Area Network (CAN) data bus.
The four-wheel drive indicator is completely controlled by the instrument cluster logic circuit, and that logic will only allow this indicator to operate
when the instrument cluster receives a battery current input on the fused ignition switch output (run-start) circuit. Therefore, the indicator will always be
OFF when the ignition switch is in any position except ON or START. The indicator only illuminates when it is energized by the instrument cluster logic
circuit. The instrument cluster will turn ON the four-wheel drive indicator for the following reasons:
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Four-Wheel Drive Indicator Lamp-On Message - Each time the cluster receives an electronic four-wheel drive indicator lamp-ON message
from the TIPM indicating that a four-wheel drive mode is selected, the four-wheel drive indicator is illuminated. The indicator remains illuminated
until the cluster receives a lamp-OFF message from the TIPM, or until the ignition switch is turned to the OFF position, whichever occurs first.
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Actuator Test - Each time the cluster is put through the actuator test, the four-wheel drive indicator will be turned ON, then OFF again during the
Vacuum Fluorescent Display (VFD) portion (domestic market vehicles) or the Light Emitting Diode (LED) portion (export market vehicles) of the
test in order to confirm the functionality of the VFD or LED and the cluster control circuitry.
The TIPM continually monitors inputs from the four-wheel drive switch to determine the status of the transfer case. The TIPM then sends the proper
lamp-ON or lamp-OFF message to the Electromechanical Instrument Cluster (EMIC) (also known as the Cab Compartment Node/CCN).
For proper diagnosis of the four-wheel drive switch, the EMIC, the TIPM, the CAN data bus or the electronic communication related to four-wheel drive
indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.
