The other day i switched my Blazer into 4 High with the electric switch to climb a small hill and cut my truck off after disengaging 4WD. Later that day i tried to put my it into 4 High and got nothing, the lights didn't flash at all and didn't feel it engage. I put it into neutral and tried and got 3 simultaneous flashing from both high and low then nothing. Anyone have any tips on where to start or had the same problem? Thanks!

 

First thing I'd do is check for codes, A & J. I'm sure you have some, then ,the next thing I'd do is "clear the codes". If you don't know how, yell, it's quite involved. The Encoder switch is fickle on these units. Sometimes it forgets where it's at and gets quite confussed....lol....did the same thing on mine and worked great...no problem switching back and forth now.

 

transfer case encoder motor. its an electric motor that shifts the t-case into 4x4 had the same problem. push 4hi and the lights would just blink. try putting it in nutral and pushing 4lo and if it engages then its the encoder motor. they run pretty cheap at junkyards but a brand new one is costly. but on mine i had a hard time getting it to go back into 2hi when in 4lo cause the motor was weak.

 

Had the same problem. As Magmotor says the Encoder Switch might forget what position it's in. Try his fix first. Unfortunately it's not a servicable Part if it is bad. My Codes kept showing an Encoder problem. Mine turned out to be the Transfer Motor. They are not as expensive as they used to be. When mine went a friend of mine was working for a Chevy Dealer & his price was $450.00 at that time. I went a couple years without 4 wheel drive until I found a new one on E-Bay for $168.00 & I haven't had a problem since. Money well spent I thought. That was about 6 years ago. Not hard to replace either. Good Luck.

 

most of the time its the vacuum accuater under the battery