I have been doing some searching for some clarification about P1876 Transfer Case 2-Wheel Drive Solenoid Circuit Failure.

Can someone tell me what this code means?

 

There is a solenoid on the passenger side of the transfer case. This is the solenoid that engages/disengages the transfer case when you rotate the 4wd switch on the dash. When you turn the switch you can hear the solenoid engage.

You can do a test. Have someone visually verify the front driveshaft is rotating when you put it in 4wd. If not the solenoid is probably bad. Does the 4wd light come on in the dash?

If your truck is stuck in 4wd then that is a different story.


Here is a link you can check.

4wd test procedure

 

So, if my Ex, which has ESOF, is not going into 4X4 and the HVAC system does not default to defrost when 4X4 is engaged, it could be this solenoid?

 

Yes. The driveshaft will spin whether the esof is engaged or not if the solenoid is working correctly. If the solenoid has failed then the front driveshaft wont spin and the hubs wont be a factor. If the front driveshaft spins then it is probably something else unless the transfer case is stuck in 4wd.