I made a Uturn on what I thought was a solid patch of dirt but was actually mud and I sunk. Reverse was useless as expected but when I locked my hubs and put it in 4 high the light didn’t come on, and only my real wheels spun. But when I put it in 4low the light came on and she backed out perfectly fine. What would cause 4 low to work but not four high? want to get some ideas before I try and troubleshoot

it’s a 86 2.3 5spd with a manual tcase

 

Welcome to the forum

The shift fork for 4WD may not have engaged the chain gear enough to get 4WD, moving shifter farther to 4low did

4WD engages when the main shaft to rear wheels is locked to the front wheel's chain drive that's on the main shaft

4high and 4low are a different part in the transfer case that uses a Planetary gear set to change the ratio of the main shaft

So there are two different things going on when shifting from 2WD to 4WD and from 4high to 4low