Ok I have a 2001 blazer with about 130,00 miles on it and the 4x4 has randomly stopped working. When I engage the 4wd the lights keep flashing and I can hear a electric motor sound underneath but, the front will not lock in . After looking for directions on where to begin troubleshooting I started by removing the battery and tray, I did not see any damage to the rubber diaphragm on the accuator or vaccum lines but it does not even try to move when I engage 4x4 , the cable can be moved by hand but does feel a little bit tight . I also checked the vaccum accuator valve solenoid on the firewall and I do have good vaccum. When I engage 4lo the rear does lock in , does this sound like the cable? I did disconnect it from the axel to see if it was seized up . Any help would be greatly appreciated !

 

You said " When I engage 4lo the rear does lock in " did you mean to say front does lock in ?...the rear is always locked in.

 

No the front will not lock in , both 4hi and lo only flash when you hit the button but when you hit 4lo the rear locks into the low gear like the front is locked in but the front tires are not pulling.

 

Do you have good vacuum pulling through the solenoid on the fire wall ? , This solenoid can be bypassed direct to see if the front will lock in.

 

Yes it appears to have good vaccum on the solenoid on the firewall and how can you bypass it ? Thank you very much for the help !!! I have seen the kits that they sell to bypass the accuator under the battery tray but if it turns out to be a simple fix I would like it to stay factory , thanks again for the help

 

I have used a plastic junction like you can find in the vacuum system or wiper hose system to connect the vacuum hoses together at the valve.... there is an in and an out that just need to be connected together .....if this doesnt lock the front then it is either the actuator under the bat tray, the cable or internal front diff......I have unstuck the firewall solenoid with a light smack from a hammer on a friends truck that was not passing vacuum through the valve....the dash switch was flashing like yours is .

 

Ok I will try that tommorow and see what happens, I'm thinking it's either the solenoid on the firewall or the cable itself.... I hope! I don't think the 4x4 has ever really been used or been put in mud so I'm hoping nothing major is wrong at this point

 

Make sure that vacuum hose that goes into the drivers side fender is in good shape and hasn't fallen off. If it's off or leaking, you can't get into 4-wheel drive. I believe the line connects to a vacuum ball inside the fender. You can't see the hole in the fender, cause it's hidden by a flange, but you can feel it with your hand. there's a little nipple right inside the hole that the line connects to. Mines a '99'. I think yours may be similar. (See attached photo's)

 

Ok , so finally got around to working on my blazer and I disconnected the 2 hoses from the solenoid on the firewall , engaged 4hi and put the 2 hoses together then went inside and the light was no longer flashing, hit 4lo and again no flashing!!!! 4×4 is now working properly engaging into 4x4 and 2wd just fine with those hoses just disconnected,so I taped the hoses together to bypass the solenoi, so now my question is , will there be any harm in leaving that way until I can replace the solenoid ?

 

It's been a while since I've messed with that solenoid, but I would check to make sure it's not drawing constant vaccumn (while in 2wd) to the actuator under the battery tray.

As long as it's not drawing vaccumn at the actuator while in 2wd, it shouldn't cause an issue