I have a early model 1999 (older body style) Tahoe. I'm having issues with the 4wd. The light on the selector switch says it's in 4wd but the it isn't. It also won't let me select 2wd, 4low etc. Its a new 4wd selector switch, tried the old one which still works and that didn't change anything. Tried a new 4wd actuator and that didn't fix anything. Fuses are all good, grounds too. The only thing that seemed to fix it was I disconnected the battery for and hour and it reset everything. The problem was the next day it was doing the same thing again. There is a CEL on so I"m getting a code reader today to check it.

Any other things I should look at? Relays?

Thanks for any help

 

Could be a bad actuator on the transfer case. A code reader might pick that up.