I had just bought a 99 blazer and when u push the button for 4x4(which theres 3 buttons, 2hi, 4hi, 2lo) it just clicked to the relay and the lights just went out. I was told it would porbbly would be the transfer case shifter motor, so i got one today and put it on. When i started it up and hit the 4hi button and it nothing happened. I tried it into neautral and nothing happened. So i tried hitting 4lo and i could defintly hear it enageing but while it is both 4hi and 4 lo lights were on and sometimes after you hear it engage both lights would stay on and sometimes all of them would e out, but it was still in 4lo. Once it was in 4lo if i hit 2hi or 4hi the 4x4 would disengage and id be in 2x4. What might be causeing it not to go into 4hi an when i hit 4 hi it does nothing unless 4lo is engaged and it it will disengage the 4x4. Please help me out in finding out what is going on im will to try anything that will help. THANKS

 

As stated in other threads, check the vacuum at the actuator, and also check the rubber housing on the actuator to make sure that the actuator is working properly. It is not stated in your question, but have you checked fluid level in front diff?

 

It just seems to be electronic or something bc sometimes the lights are on and sometimes there not.

 

Just wanted to say i tried unhooking the battery this morning for 30 mins and when i hooked it up everything was working fine other than the 4hi button wasent staying on. I took it for a drive and when i turned a corner it seemed like the whole truck went into neutral and wouldnt move. I had to put it trans into neutal and push the 4hi button which put it into 2hi and im back to the same thing only 4lo works. Does that sound like something electrical?

 

dude my 4x4 wasnt working either, i thought it was but when i would push 4hi i wouldnt hear a clunk but when i would push 4lo i would. it would clunk and i could definitely feel the lower gearing. maybe thats what you feel in 4lo (just the clunk and lower gearing- kinda feels like 4lo but when you turn you wont feel the front pulling). i recommend putting your truck on all 4 jackstands and taking the battery out, taking the battery tray out, wiggle one of the front wheels, manually squeeze the actuator and if it clicks in, put everything back turn it on, put in 4hi and pray.

thats how i got mine to work, then i tore all that crap off and put a pull cable setup into the cab.

 

i don't know if you aready did this, but why not start at the switch? it's the cheapest to do (by alot).
i had the exact same thing with my '98 when i bought it. would only go into 4HI if i engauged 4LO first, put it in gear, rolled like 12", stopped, then tried 4HI. but it would disengauge on it's own sometimes (usually when the snow was blowing all over the roads!). i refused to pay the price for the servo on the transfer case (which is what alot of ppl were telling me the problem was), even though i was getting it for cost at the dealer. i waited, found a truck with a puked engine (for the servo), but then noticed right after i stripped the truck, that my switch wouldn't light up anymore. changed the switch, no more problems. only problem now, is the mass of parts i accumulated at my house (can you hear my wife fumming now, hahahaha).
before you spend anymore money, why not get the switch checked out.

 

Yea i have already tied the switch on the dash and it does the same thing. I just cant figure out why when i unhook the battery it works fine until i disengage and then it acks up again. Does anyone hae and pics of the acuator under the battery. I dot know much about it.

 

dude u dont need pictures...just unhook your battery and remove the tray underneath it......and bam theres the actuator.. its easier to learn when you got in front of you.

 

it looks like the vacuum diaphragm that's used for the cruise control.