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Unread 04-17-2010, 11:02 AM   #1
TrynPas
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T-case vacuum switch actuator?

Ever since I bought my jeep (about two months ago) I haven't been able to use the 4wd. I took the t-case apart and with the help of RustyWrangler found that my shift mode fork pads were missing (thanks again Rusty). With that problem fixed, I now needed to replace the vacuum switch on the t-case. I did that but it still isn't engaging the front axle. I took the switch back out and activated it by hand and it is working so I'm guessing it's whatever actuates the switch that has a problem. Can anyone tell me what I'll need to replace? I'd rather get the part(s) now so when I take it apart I can just replace it. Thanks in advance for the help. Oh yeah, I don't really want a cable 'posi-lok'. I'm sure they work great but I don't really like how they look hanging out of the axle (the ones I've seen at least).

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Unread 04-17-2010, 11:16 AM   #2
xdgt03
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Make sure the vacuum hoses are attached to vacuum and are solidly on the actuator. Also, I think it can mistakenly be installed with the forks on the outside of the collar. I can't remember from when I changed mine but I think it can happen. Check for voltage at the harness.
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Unread 04-17-2010, 11:21 AM   #3
TrynPas
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Quote:
Originally Posted by xdgt03 View Post
Make sure the vacuum hoses are attached to vacuum and are solidly on the actuator. Also, I think it can mistakenly be installed with the forks on the outside of the collar. I can't remember from when I changed mine but I think it can happen. Check for voltage at the harness.
it's completely on there. I 'lubed' it with some saliva and it slid down tight. When you say 'forks', are you referring to the two plastic tabs on the vacuum switch to make sure you put the plug on correctly? if so, they they are correct. when the switch is in my hand and plugged into the vacuum plug everthing works great, that's why I think it's the actuator inside the t-case.
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Unread 04-17-2010, 11:27 AM   #4
justpicaname
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I have the same problem, I took the actuator off(on front axle). The fork was seized. There is some rust flaking off on the inside, and is getting plugged up in the diaphram. I cleanded it all out, so the fork was sliding easy. I put it back on and still no 4x4. I'm thinking maybe I'll pull it apart again, maybe the fork didn't seat properly or maybe jamed up with rust again.
You may have a similer problem?
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Unread 04-17-2010, 11:29 AM   #5
xdgt03
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The actuator bolts on to the axle. Where it bolts on there is a fork lever. The lever (if I remember correctly) can sit on the outside of the collar that moves back and forth on the axle to engage the front axle for 4wd.
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Unread 04-17-2010, 11:30 AM   #6
TrynPas
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I think I used the wrong terminology. My problem isn't at the front axle, it's back at the t-case where the vacuum 'switch' is. it's not being activated whenever I shift the t-case into 4wd.
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Unread 04-17-2010, 11:56 AM   #7
xdgt03
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Ah. I think I just misread what you were saying. Let me check my manual.
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Unread 04-17-2010, 12:37 PM   #8
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You changed the pads on the range fork by taking the tcase apart? The only other suggestion I would have had was to check the fluid level and the linkage for binding. I assume you already did this.
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Unread 04-17-2010, 01:02 PM   #9
TrynPas
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Quote:
Originally Posted by xdgt03 View Post
You changed the pads on the range fork by taking the tcase apart? The only other suggestion I would have had was to check the fluid level and the linkage for binding. I assume you already did this.
I only changed the pads on what I think is called the 'shift mode' fork, which is the rear most fork. I did not change the other fork pads as they were still intact. Fluid level is good, made an adjustment to the linkage today, but it seems to be working correctly. It was out of adjustment alittle to begin with, it would slip out of 4Lo so now it does not.
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Unread 04-17-2010, 01:26 PM   #10
myblackyj
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i just hade that same problem i siad **** this and did the tj swap
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Unread 04-17-2010, 07:53 PM   #11
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Is the red line connected to a vacuum source on the manifold? There should also be a line (blue?) that looks like it isn't connected to anything, this would be your vent.
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Unread 04-17-2010, 08:41 PM   #12
jay-h
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Quote:
Originally Posted by myblackyj View Post
i just hade that same problem i siad **** this and did the tj swap
I think he's talking about the forks in the TC, not on the front axle
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Unread 04-17-2010, 09:12 PM   #13
UltimatE
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Are you positive the front axle CAD is working properly? It is the culprit 99% of the time. The vacuum comes from the engine, 2 hoses go to the CAD, and one is a vent. There are only 4 possibilities for a fault: Lack of vacuum, the t-case switch and/or internals, the vacuum lines, or the front axle CAD.

Easiest way to make a definitive answer as to whether or not the transfer case is the issues, is to remove the switch from the T-case, connect the hoses and start the jeep. Actuate the switch by hand and see if the CAD actuates. If it does, then the T-case internals are to fault. If it does not, either you have no vacuum, the hoses are cracked, or the CAD is faulty.
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Unread 04-18-2010, 07:15 AM   #14
jay-h
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Easier way to check the front axle. Hook up one side, then the other to direct manifold vacuum. See if it switches. I have had my share of problems with the TC switch. I replaced it about a year ago, and it's acting up again. It applies vac (as tested with a gage) to the 4wd side when in 4wd, but does not apply vac to the 2wd side when in 2wd.Checked the hoses for leakage. Since it is not really problematic to switch in and out of 4wd while leaving the front axle engaged, I'm thinking of just using a barb connection setup. Leaving the front axle open during my daily drive stuff, switching the connection when I anticipate using the 4wd.
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Unread 04-19-2010, 12:35 AM   #15
TrynPas
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found the problem. seems that the vacuum plug at the front axle was on backwards. I did have a bad vacuum switch to start with, so when that was replaced I had it in 4wd to try and get the front axle (and the indicator light) on. Finally I gave up and was going to the store, so when I put it in 2wd the 4wd indicator light came on, which told me that the front plug (or something) was backwards. I turned it around and it works great. It's a little short, but it works. Can anyone tell me which way the vacuum lines come out of the front axle plug? Mine come out of the back (towards rear of vehicle).
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