Just bought this used 2021 Ram 1500 Big Horn 3 months ago with 13,500 miles on it. At about 15,000 miles the Service 4WD yellow light came on. After having my mechanic check and change all the relevant fluids, the service light remained on. So I took it to a dealer to get the final answer on what additional was needed to be serviced, because switching between two and four-wheel-drive was functioning properly. The dealer has ordered the replacement “front differential lock actuator” part and will call me to schedule the work when it arrives.

There are lots of forum and YouTube posts about this same problem. The dealer said if this was not a warranty repair it would be over a $1,000.00 job. If the same thing happens again in the next few months, I will certainly be looking for a more cost wise vehicle.