RAM 1500 Truck 4WD V8-4.7L (2008)
the Totally Integrated Power Module (TIPM) over the Controller Area Network (CAN) data bus.
The 4 low indicator Light Emitting Diode (LED) 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 LED
will always be OFF when the ignition switch is in any position except ON or START. The LED only illuminates when it is provided a path to ground by
the instrument cluster transistor. The instrument cluster will turn ON the 4 low indicator for the following reasons:
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4 Low Indicator Lamp-On Message - Each time the cluster receives an electronic 4 low indicator lamp-ON message from the TIPM, the
indicator will be 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 4 low indicator will be turned ON, then OFF again during the LED
portion of the test to confirm the functionality of the LED and the cluster control circuitry.
The TIPM continually monitors the electronic transfer case through the transfer case shift motor/mode sensor assembly to determine when the 4WD low
mode is engaged. 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 further diagnosis of the 4 low indicator or the instrument cluster circuitry that controls the LED, Refer to
appropriate testing.
For proper diagnosis of the transfer case shift motor/mode sensor, the TIPM, the EMIC, the CAN data bus or the electronic communication related to 4
low indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.
