1999 siverado 4wd problem..started having problems coming out of 4wd, pushed 2wd dash indicator said 2wd but not in any gear. put in park, got grinding gear sound shut off engine restarted 2wd active now. this happend 3 times over about a month. now it wont even go into 4wd I hear transfer case shift into 4wd low but not in 4wd high. boy why couldnt they leave the manual hubs and shift lever alone?? lock hubs before you need 4wd and just use shift lever in cab.hehe

for 4wl need to be stopped and put in neutral or park it wont actuate while driving [ blinking light indicates failure to engage ] 4wd hi can do while driving --if fails also then check and test for actuator sticking --control module --or transfer case failure

i would check the cervo motor on the transfer case and listen for it to shift it out that might be bad or else it might be the electronic 4wd computer under the dash on the drivers side that might be bad or the solenoid on the transfer case might be shot. your best bet is to get a continuity tester and start at the actuator on the front end and see where the power is not coming through. to unlock it from 4wd unhook the actuator on the front diff. and see if it unlocks by pushing the button

The actuator has a spring that is known to break easily in mid-late 90's chevy's.

Sounds like the encoder switch is bad ..it on the transfer case .it has a motor with wires going to it.when you press the button it sends a signal to that motor to switch into a certain gear..

there are bulletins on this the diff actuator could be bad or the switch on the transfer case is sticking

i had the same problem in my 99,i replaced the switch assembly on the dash and all is well,hope this helps

try putting in nuetral and then shift into high gear . if still does not work sounds like the 4x4 acctuator is bad

sound like problems in transfer case shift module.

ok this is easy,put the truck in park and put your foot on the brake then push the button

there is a actuator on the front differential that commonly goes out. spendy fix but that will fix your problem