Hi, new forum member here and I need some help.

I have a 98 Chevy Blazer LS 4x4 and the 4x4 is acting strange and I am completely miffed. It runs fine in 2wd, but when i press the 4x4 HI button (on the fly) to engage the 4x4 HI I do not think its engaging. I can hear a click behind the dash, the 4x4 HI button indicator switched from 2wd to 4x4 HI and it sounds like the front axel is trying to engage but the blazer doesn't drive or sound any different. The screwy part is 4x4 LOW is working just fine. It engages just fine when the the vehicle is stopped and in neutral, 4x4 LOW is engaged and then back to drive. Also, nothing lights up indicating the 4x4 function on the bezel/dash area. Any help would be great

 

First off, try pulling your tccm fuse for 30 minutes for a tccm relearn.

 

My guess is you dont have vacuum getting to the actuator that engages the front axle. If the lights stay lit and dont flash then nothing is wrong with the TCCM i dont believe. Luckily vacuum is pretty easy to diagnose.

You say 4LO works but my guess is the front axle doesnt engage, it will still go into low gear tho. So put it in 4WD and get to some wet grass or something slippery hit the gas and see if the front tires spin. Or you can just put it in 4WD and try to turn SLOW on dry pavement and see if the inside front tire slips. Thats not good for the front end if it does engage tho.

 

+1, check the actuator under the battery and also the solenoid mounted on the fire wall and start checking vacuum lines.

 

i was thrown off by the " Also, nothing lights up indicating the 4x4 function on the bezel/dash area."
In that case, check vac lines

 

Close to the same problem on my 97, Front end will not lock in, But you can feel the accuator cable trying to move.....Is the cable bad and not locking in the front axle ?

 

Do you have control on where you're heat blows? Hvac controls?

 

I do yes