At 80,000 miles bought a 5500 lb trailer, changed trans and transfer/diffs and towed 5k miles, happy R51. Did a 2nd 4 qt transmission change at 85,000 miles.

Last night going up a steeeep hill in 2nd gear and 2wd, 4WD light and service engine light comes on, engine continues to run but when I stepped on the gas, the truck would not drive despite rpm's climbing.

Truck off 15 minutes, checked trans fluid (clear pink, full, perhaps a burning smell?), checked transfer level (again seems full and pink, tiny leak perhaps at drain plug where my dad forgot washer), oil normal. After 15 minutes, 4WD light off, truck goes in to 4wd no issue, drives normal. After 5 miles let it rest for the night.

This morning it repeat after about 3 hours of mountain driving, 4wd light on solid, loss of power to wheels, waited 20 minutes drives normal.

What am I experiencing? Loss of power sounds like trans. But why this indicator light? Could it just be a sensor?

I'm no pro at checking levels but when I curl up a lint free rag in to transfer filler plug it has pink atf at like 1/8". Seems clean and full, just changed 5k miles ago.

I've searched and searched and have not found this scenario do anyone who can help a guy stuck in the hills of Idaho Idappreciated it! I'm stealing a motel's wifi as we speak lol

Best thing to do would be to retrieve the 4WD trouble codes. Unless you have access to a capable scanner to retrieve the 4WD codes in your Nissan, it's kind of hard to say what is going on.