Today I went in the mountain to find snow on a pike... Problem, when I was on ice I pressed on 4WD, and I stayed in RWD....

This is a 1995 Blazer 4.3.

I can hear the relay, and the transfer case knocking, but nothing happens on the front wheels....

I've tried 4HI and 4LO.

Maybe a problem in the transfer case ?

 

First place to check is the vacuum actuator under the battery tray. This receives vacuum from a switch on the transfer case and is one of the most common points of failure. The vacuum hose can become disconnected from the actuator, or the rubber diaphragm can get worn and torn. Another vacuum hose to check is the one connected to the reservoir ball on underside of the hood on the driver's side of the of the truck. It will be near the brake booster. If there is a vacuum leak anywhere on these hoses the actuator won't develop enough pressure to engage the front differential.

 

Ok thanks. So when I press on 4HI or 4LO ( in neutral ), I must see this actuator move... Does it works with engine off ?

 

 

Cool thanks ! I'll check it !
But when that actuator doesn't work, the transfert case still move ?

 

When the actuator doesn't work, the transfer case should still engage the front drive shaft, but the actuator doesn't connect the drive input to the axles.

 

Well, I've fixed it ! That was the vacuum actuator hose. It was porous. Now I can go in the snow

Thanks guys for all your advices

 

Great! Thanks for posting back to let us know you fixed your problem.