service 4wd light

[chuckgrif]

I have a 2008 ram 2500 4wd . im having an issue where the serv 4wd light comes on and right after the the truck then shifts itself into 4wd it doesnt alway light the 4wd light on the dash. Sometimes it will light it or it will put itself in 4 wheel lo and light the light. you cant turn the dial to get it unlocked the only way to get it out of 4wd is to depress the n button under the switch then it will operate normal. Ive had the transfer case actuator motor replaced mech found if a certain pin has more than 3 volts the actuator is bad ,we had 4 volts replaced actuator and everything seemed fine then it happened again about 150 miles later.

 

[Timd32]

Any codes?

Here the 1000' from the manual for the light in general, not super helpful I know. It's controlled from the TIPM, which monitors the XC.
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The TIPM continually monitors the electronic transfer case control circuits and transfer case shift motor/mode sensor assembly to determine the condition of the system. 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 service 4WD indicator or the instrument cluster circuitry that controls the LED, Refer to appropriate testing.

For proper diagnosis of the TIPM, the EMIC, the CAN data bus or the electronic communication related to service 4WD indicator operation a diagnostic scan tool is required. Refer to the appropriate diagnostic information.

 

[Ozymandias]

Dash switch is well known to fail.