Need Transfer Case Vacuum Switch Help - JeepForum.com
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post #1 of 27 Old 01-23-2009, 10:37 AM Thread Starter
MDonovan8
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Need Transfer Case Vacuum Switch Help

I have a '94 Wrangler YJ that the vacuum lines rotted and I am atempting to put back together. All the diagrams that I have found show red (source), green (unlock), blue (vent) and yellow (lock). Well as luck would have it none of the lines are color coded on my Jeep and I need to know where each line plugs into the vacuum switch on the transfer case. All the diagrams show a round vacuum plug when mine is square. I have traced all of the lines and marked them according to the color code, but can not figure out where each line goes on the plug itself. I have spent 2 days trying to research this but like I said the diagrams are not helping. HELP!!!!

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post #2 of 27 Old 01-23-2009, 11:21 AM
kloppk
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Quote:
Originally Posted by MDonovan8 View Post
I have a '94 Wrangler YJ that the vacuum lines rotted and I am atempting to put back together. All the diagrams that I have found show red (source), green (unlock), blue (vent) and yellow (lock). Well as luck would have it none of the lines are color coded on my Jeep and I need to know where each line plugs into the vacuum switch on the transfer case. All the diagrams show a round vacuum plug when mine is square. I have traced all of the lines and marked them according to the color code, but can not figure out where each line goes on the plug itself. I have spent 2 days trying to research this but like I said the diagrams are not helping. HELP!!!!
These two should help you...



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post #3 of 27 Old 01-23-2009, 07:00 PM Thread Starter
MDonovan8
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I have both of these diagrams, they don't help me because my plug is square and not round.
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post #4 of 27 Old 01-23-2009, 07:18 PM
kloppk
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A square one is not the OEM setup.
Sounds like someone in the past swapped out the round factory plug and the vacuum switch on the tcase to some oddball square one.

Basically the vacuum switch on the tcase does the following.
In 2WD mode the vacuum source (RED) is routed by the switch to the (GREEN) Unlock line and the Vent is routed to the YELLOW.
In 4WD mode the switch routes the vacuum source (RED) to the lock (YELLOW) and connects the Vent to the unlock (GREEN) line.
You should be able to shift the tcase into these two modes and determine which ports on your square switch behave like the above. Once you figure that out then run your 4 tubes to the appropriate points on your setup.
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post #5 of 27 Old 01-23-2009, 07:25 PM Thread Starter
MDonovan8
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I am beginning to figure out that one of the previous owners did some work to this Jeep. None of the vacuum lines are color coded which may suggest that they were changed.
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post #6 of 27 Old 01-23-2009, 07:28 PM Thread Starter
MDonovan8
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You have been more help than anyone I have talked to.
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post #7 of 27 Old 01-23-2009, 07:52 PM
Burnerman
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You can use a piece of rubber hose and trial and error method. Hook the hose to one of the ports and blow in it with the tcase in 2h. Mark the port air comes out of. do the same in 4h. The vent line relieves the vacuum between the yellow and green. It may take a bit and will be easier if you remove the shifter plate on the floor. Or buy a new switch. Make sure you keep the new hoses bundled together, marked at both ends, plenty of slack for axle droop and away from the hot exhaust.

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post #8 of 27 Old 03-07-2009, 01:53 PM
SECorBust
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vacuum switch

I'm working on my vacuum setup today. I thought that I'd mention that my plugs are square on my 95 rio grande. Chrysler has swiched to the round plugs on the newer stuff I think.

I unscrewed the vacuum swich and pressed the ball with the engine running to ensure that my switch was working. For some reason my t-case is not pressing the valve or ball or whatever far enough up into the switch (I recently put on a newer NP231), so I'm not sure what the problem is.

Suction comes from the intake down to the port on the switch with the two alignment tabs. When the switch is not activated the vacuum goes to the line to the right of the one with vacuum when looking at the disconnected vacuum plug from the bottom. When the switch is pressed the vacuum is supposed to be transferred to the line to the right of the line with tabs on either side to activate the 4x4.
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post #9 of 27 Old 05-22-2009, 09:25 PM
nyquiljunkie
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so, the 'indicator switch' in the above pic is what turns on the dashboard 4WD light?

I'm trying to figure out why her 91 yj's 4wd light doesnt come on and I tripped over this thread.

I'm reasonably sure the 4wd kicks in when you shift to 4H, I can feel the obvious difference in steering it (on gravel).
But the &%$#!@ light wont come on. I've read in the service books there is a "command trac switch' under the battery. No there is nothing under the battery. I did find a black vac line cut and dangling by the battery....
I have to do some careful study of where these vac lines (all black) are going, but the indicator switch on hers IS on the font axle beside/on the shift motor housing.
well I think its the indicator switch anyway.

So confused I am... this switch turns on the dash light?
Can it be taken out and cleaned? (does that work?) Is it stuck or do they just burn out?

I'm not finding a switch on the firewall either.
if I cant figure it out with a few friendly replies in this thread I'll take some detail photos and start a whole new thread on the problem.

Thanks!

The Jeeps are hers. The tools are mine. She drives them, I fix them. Lucky me.
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post #10 of 27 Old 05-22-2009, 09:42 PM
shatteredsoul
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My 4wd switch on the firewall is long gone thanks to the PO my 4wd system shifts fine from 2wd to 4wd now.I had to replace the switch at thw Tcase as well as the actuator at the diff.So basically on mine red is a vac source off the carb,blue is a vent,yellow locks it and has no hose to a firewall switch.You will definately know if its locked or not but just to make sure the front drive shaft will spin freely if its not locked(Engine off) and wont turn when locked(Again engine off) dont try with engine running.
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post #11 of 27 Old 05-22-2009, 09:42 PM
green89yj
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try checking in my last thread about convince me to posi-lok. I will get a link up soon. I will have some time tomorrow to check. You can go to advanced and buy the round transfer case plug if it is giving you that much trouble. Look in the misc parts section.


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post #12 of 27 Old 05-22-2009, 09:43 PM
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Here is the link. Hope it helps. http://www.jeepforum.com/forum/f12/convince-me-posi-lok-752208/


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WTT: 4" springs for 6"
WTS: 4.2 parts. Fuel lines, pump, block, head, accessories, just ask
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post #13 of 27 Old 05-22-2009, 10:09 PM
kirksjeep
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Another option is to ditch the vacuum system and put in a solid shaft out of a XJ or TJ. Plus if you get a shaft from a 96+you also get the bigger U-joints. Only need three parts, the shaft, NAPA inner seal 11800, and fab up a simple block off plate to replace the vacuum set up.

To get the light to work you can use an electric TJ switch and you are set.
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post #14 of 27 Old 05-22-2009, 10:16 PM
buckshot500
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When you use the posi-lok, you can remove all the vacuum lines from the T-case switch plug, & fill the empty holes with silicone sealer. This way, it will protect the switch from mud, should you ever decide to use it again, or sell your T-case, when you get an Atlas.

Quote:
Originally Posted by 5point1 View Post
Well after I drained the oil, I ran water through the engine to clean out the gunk. (the guy who owned before me obvioulsy didn't know how to maintain the engine).

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post #15 of 27 Old 05-22-2009, 10:16 PM
nyquiljunkie
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I'm not into making it better, just making the factory switches work again.

She rarely ever uses 4wd anyway. It just bugs me the light wont come on.

LOL

If its just switches and vac hose, replacing one or all those is good enough.

Just so it works the way it was designed to again.

The Jeeps are hers. The tools are mine. She drives them, I fix them. Lucky me.
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