I have an 04 4wd blazer with the three push buttons in the dash 2wd works fine so does 4Lo but when i push the 4hi button the 4hi and low buttons just flash and the truck goes back into 2wd what could this be thanks for your help

 

actuator/motor

its one part, check your vacuum lines are not dry rotted. also in the manual there is a way to make it go into 4wd hi. cant remember how you do it. (its different then just pushing the button, its a sequence). its in the section about 4wd.

 

yea i noticed today (of all days) that i dont have 4hi. i have 4lo but that dosent help gettin down the road with 6in of snow. i can hear the transfer case shift when i push the button but what the crap. also i have a posi lock system to engage my front diff. and i know its good.

 

"posi lock-is the locking of both front tires to spin at the same time. also known as a front differential. if your blazer is stock it doesn not have "posi lock". are you talking the diu posi-lock cable setup, with the write up on here?

 

ok will do some checking in the morning

 

the actuators/motors are a pretty common failure, although i've seen a handfull of vac leaks cause this

 

i got it working unhooked the battery for 30 minutes and then hooked it back up works great but now my speedometer is pegged out at 100 any suggestions on how to fix this

 

try ressetting your computer by taking the battery cable off again for 30 minutes. then rock it back and forth between drive and reverse. after you've hooked the cable back up and the trucks on