Hello i have a 2001 chevy blazer lt 4x4. Im experiencing a problem where the 4x4 will not disengage. Also there is no lights that light up when pushed. I do here the actuator try to disengage, makes a buzzing noise. Also i notice a noice coming from the passenger side kick panel. When i was looking under the truck i noticed there is a vacuum line on top of the trans that is not connected to anywhere, could someone help me out as i am new to 4x4 but mechanically inclined about vehicles. thanks

 

oops hear and noise lol

 

The vacuum line on top of the trans is likely the one that is supposed to go the vaccum switch which disengages the front differential.

Best suggestion is to search on here; use words like: 4wd, vacuum switch....etc. More information that I can even begin to type-out myself.

 

ok i removed the battery tray and checked the actuator. the unit looks in good shape, the cable shifts when pulled, and there is suction on the vacuum line. i also traced the line to the center of the firewall and when i squeeze the actuator it makes a whoosh noise at the solenoid. does this vacuum area post to make any noise at all? the engine is off when i do this. somebody also mentioned that tc motor might be bad. is there anyway of telling if it is? i also tried looking on the trans for that vacuum switch and called autozone to see if there is a part number for it and there is none. my truck is getting very poor ga mileage and would like to try and fix it. meineke also told me that they will charge 85 to determine what the problem. is this expensive? thanks for replying by the way.

 

I had a similar problem and it turned out to be the transfer case motor needed to be replaced...

Do you ever have any lights on the 4wd selector? Which do you have? The four button one with auto, 2hi, 4lo, and 4hi?

You could check the atc fuse under the hood and the 4x4 fuse by the door. Also the wiring to/from the tccm and transfer case motor. The tccm is located under that kick panel.

Other than inspecting wires and fuses for obvious damage I'm not sure how to definitively test the tccm or transfer case motor. To get the diagnostic codes you need to connect one of the pins on the port below the instrument panel to ground and the selector lights indicate what code its giving. You should be able to find more information about that somewhere around here..

Not sure how good of an idea this is, but you could remove the front drive shaft until you are able to get it fixed.

Also I think this should be posted under the steering, suspension, & drivetrain section.

 

sorry for the long return back. my truck has the four buttons that say 2hi 4hi 4lo 4wauto. when the truck sits for a long time, i restart it and the 4hi is lit. when i start dring the service light comes on then the lights go blank. i removed the driveshaft earlier this afternoon and noticed a difference in the truck. i do believe and i might be wrong but if i do have to replace tc motor i would have to remove the shaft anyways. i noticed after driving that there is no leaks coming from the output shaft for the front axle. any other ideas maybe? thanks for the help by the way

 

check plug to tccm , may be coroded! or you may have a tccm problem , there is a plug two wire on the front axel housing you can unplug it and the computer will go to default 2 wheel hi. then plug it back in so it doesnt get stuff in the plug. this is usually a sign that one side of the tccm isnt working . had a simular problem , mine was stuck in 4 wheel low! I changed the switch first, then the tccm. It works good now the switch wasnt the problem the plug was coroded on the tccm. i used a deoxidise spray then dialectric grease after I replaced the tccm.