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Unread 01-08-2012, 10:36 AM   #1
fishnic
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1988 YJ Wrangler 
 
Join Date: Nov 2008
Location: 60714
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4wd vacuum actuator - vacuum troubleshoot

I tested the vacuum at the transfer case switch - 20lbs at the red line.

When shifter is in 2 wheel drive, I get no vacuum to the yellow or black lines running to the actuator. I do have vacuum in the green line which i believe is the indicator light.

In 4wd i get vacuum to both the yellow and black line and also to the green line.

I thought i should have vacuum to one side in 2wd and vacuum to the other in 4wd. Why am i getting it on both sides in only 4wd?

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Unread 01-08-2012, 11:01 AM   #2
ES772
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Im sure someone will correct me if im wrong, but i had the same problem and it turned out to be the Transfer Case Vacuum Switch located on the side of the transfer case. Part runs about 35$ and takes 10 minutes to change.
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Unread 01-08-2012, 11:06 AM   #3
fishnic
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below is the pic of my actuator - as u can see one nipple is rusted off - i only plan to replace it if my vacuum is running correctly otherwise i am locking it in 100%.

When i blow into or suck into the green the actuator moves back and forth
When i blow into or suck into the yellow the actuator moves back and forth

nothing happens in the black - i dont know if it is plugged or what?
actuator.jpg  
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Unread 01-08-2012, 11:16 AM   #4
another1
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e-clip fix it. Meaning take the clip out and move it over and reclip it. Try the not engaging forum. I did this and it works
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Unread 01-08-2012, 11:21 AM   #5
fishnic
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Quote:
Originally Posted by another1 View Post
e-clip fix it. Meaning take the clip out and move it over and reclip it. Try the not engaging forum. I did this and it works
yes this would be my alternate fix if the vacuum lines are incorrectly functioning. my first choice is to fix it, second replace. My thoughts are replace the transfer case switch for $20-30 and then drill the rusted actuator and insert a threaded nipple. If the vacuum is running correctly maybe i will spring the $120 for the new actuator if my plan doesnt work.
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Unread 01-08-2012, 11:36 AM   #6
fishnic
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additioanlly - if i need to swap the transfer case switch - what is the easiest way to get it out - i can see it and get my hands on it easiest from the front, but the only thing i could get near it is a crescent wrench. what socket size is it anyone know?
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Unread 01-08-2012, 11:52 AM   #7
dancytron
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Black is the indicator light (shown as white in this diagram).

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Unread 01-08-2012, 12:05 PM   #8
fishnic
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ok that makes sense - so my transfer case switch does seem to work correctly. green sucking in 2wd and yellow suction in 4wd. now to work on the actuator
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Unread 01-08-2012, 01:28 PM   #9
fishnic
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only broke the head off of 1 of the 4 actuator bolts when i removed it. Small amount of gear oil dripped out as I had the passenger side jacked up. I sanded off the gasket material. The broken bolt came out easily after giving it a few PB blasts and letting it work on a bit.

Now i plan to get a small threaded nipple the same diameter of the other nipple. Tap the broken side. Put some teflon tape on it and thread it in. I hope this will be a good Alley mechanic fix for it. Hopefully Tuesday I will be able to work on it again.

I appreciate the help in this thread - I have read all of the others and I know these pop up daily.
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Unread 01-08-2012, 05:16 PM   #10
fishnic
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question on the indicator light line - where is the switch located? does that vacuum line run all the way to the interior and turns the switch on there?
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Unread 01-08-2012, 05:32 PM   #11
Mark05059
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runs to under the battery tray on the firewall. will be a vac line and 2 wires I believe.
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Unread 01-13-2012, 02:37 PM   #12
fishnic
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Thanks for all the help -

I shouldered off the rusty hole with an easy out and tapped the hole. Threaded in a small hose barb with teflon tape on it. The fitting was a bit to small and was losing vacuum so i need a slightly larger fitting. For the time being i put 2 wraps of duct tape on the barb and put the hoses back on. Works like a charm - the 4x4 light works also. I still have the wheel jacked up as I want to give the RTV a chance to dry overnight in this cold weather. Wheel spins freely in 2 wheel and locks properly in 4 wheel.

Will test it out on pavement tomorrow!
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