So I'm going through the problems on the blazer 1 by 1 and I'm now trying to figure out why the 4wd does not work. You guys have been a huge help so far and with your suggestions I've gotten a ton of work done. Does anyone know where I should be starting in diagnosing the 4wd problem?

1994 blazer
standard transmission (5 speed)


If you need any more info about the truck let me know.

 

Can you give a better description of the what's going on? Does the light on the 4WD shifter come on? Does the truck make any noises when you try and shift it into 4WD? The first thing I would do is replace the 4WD actuator.

PartsTrain.com - Hard to Find Auto Parts and Truck Parts - 4WD Actuator For 1994 Chevrolet Blazer Silverado 8 Cyl 5.7L

 

9 times out of ten it the actuator on the front axle housing. First check the plug to make sure the connection is clean if that's good then the actuator is likely shot. There were three different designs and two of them were really well known for filling up with water and going to hell. I lucked out with my 94', it's got the 3rd type being the really well sealed up unit.

 

My 93 fullsize had a fuse blowing problem replaced actuator samething, kept blowing fuses. Checked the switch on the diff housing not the problem. I chased my wires back to where the wires run up to the fire wall " they run up a metal tube on the firewall" right in the bend where it turns up I found a skint wire which I cut soldered and heat shrunk. I hadnt a fuse blowing problem since! Now I have a CV axle going out! Oh joy!!