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98 Jimmy 4wd vaccum lines?


suzuki1750
11-22-2006, 06:48 PM
Hi all, My name is steve and i am new here.
The problem i am having is, 4wd not working. Found out actuator not working. Traced back vaccum lines and it is all rotted apart. The problem i am having is there are several vaccum lines coming from the tcase and a few of them are broken. I dont know where these lines are supposed to go. I dont know where the line from actuator goes. The crappy Haynes manual dont tell me anything. Any help would be great. Diagram or pics would be even better. Thanks

Steve

muddog321
11-25-2006, 01:56 PM
Well you are in luck cause had to do a 98 today and here's the info on the 3 port vac switch I bought a Motormite #49315 for $15 at Advance and its on the Help part isle (not listed online so don't try and look it up) lists for 1983 -2000 but think 98 was last year in Blazers. Two ways to look at it so I'll explain looking down on the plastic 3 port switch with the locator raised tab at the bottom, the port to the right is the Vac port from the engine, one to left of tab is a vent port, and the other is the vac to actuator port:
Pic of ports O to front act port
vent port O . O vac port

So when the spring loaded switch ball is down (2wd) the vac from the engine goes no where or is off (other 2 ports are open and connected together). When 4Hi is pressed an arm in the transer case pushes the ball up and the vac is applied to the front actuator port and front axle coupler engages. When 2wd pressed again the vac is removed from the front act port and it vents thru the vent port releasing the actuator. This vent port is T to a rear transfer case vent port also and the line usually runs up the trans dipstick with a small vent on it. The 3 vac lines coming in to the switch are in a formed rubber fitting that keys to the tab on the switch top so hard to get wrong. >>>>Remember that if you look into that rubber connector ports are reversed from my above description<<<<.

This was a NP 233 transfer case 3 button and for all note that the front drive shaft does NOT turn at all in 2wd - I tested and watched.

DJ_62451
06-14-2008, 05:43 PM
On my 91 Chevy S10 Blazer all the time the 4wd low light is lit when going through 2wd,4wd high,neutral,and 4wd low the light still stays on 4wd low (started after installing new clutch)

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