Hey all!

We have been having problem with the 4X4. It's a 2002 Blazer with a 3 button 4X4 switch. It wouldn't switch out of 4wd about a month ago, so I replaced the switch, and it seemed to work fine. Earlier today, it wouldn't switch out of 2WD into 4WD. I read through the great posts on here about the switch, and then I decided to check the Vacuum lines. I traced the one from the manifold to where it T's off. As you can see in the picture, the hoses T off at the Green connector. The green connector then split off again, one to the transfer case, and one through the firewall. Then there is a little hose, about 6" that was just floating out in space, not connected to anything. It is sucking air in. In the great post by SwartlKK, it says that the hose should be plugged into the "Big Black Ball." However, I have no idea what the big black ball is. Can anyone help?

I tried pulling the fuse of the TCCM, but I didn't see a 5 amp fuse for it. instead, I pulled the fuse for the 4WD in the dash panel, and tried the off to run position reset, and the button is still in 2wd and refuses to switch. However, when I put the truck in Neutral and push the 4HI button, I can hear the actuator behind the dash, and the lights light up 5 times, and then it goes back to the 2WD button.

I know that there are several posts about this, but I'm a noob, and the more I read, the more I'm confused about where to start. If anyone can help, it would be greatly appreciated!

Thanks in advance!
Ryan

 

It plugs into the vacuum reservoir which is located in the driver fender. Just about straight down from where the hose is now. Just rearward of the ABS module. Little black plastic nipple sticks out 3/4" of the fender. If you use a mirror you can see it, if you stick your hand in there, you can feel it.

 

i second this opinion i tried to reconnect mine to the reservoir but gave as i couldn't find the nipple, so i plugged it with a screw

 

Post #14 in this thread shows it:

https://blazerforum.com/forum/2nd-ge...um-line-55232/

 

However, the loss of vacuum will not prevent the transfer case motor from shifting from 2wd to 4wd, let alone screw with the lights. You have another problem going on besides the vacuum reserviour not being plugged in.