command-trac question - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

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post #1 of (permalink) Old 12-18-2000, 08:32 PM
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command-trac question

Do any of you guys know much about the YJ command-trac system? I have a 93 Wrangler with the command-trac vacuum-actuated front axle engagement system. The vacuum harness was broken, so I replaced it. Now when I shift out of 4wd, the front axle doesn't disengage. I put a vacuum pump on the shift motor and gave it 15hg and it disengaged, and it maintained the vacuum as long as I kept it on there, just like the book says it should, so apparently the shift motor is ok. Maybe I'm not getting enough suck from the transfer case? Anyone have any ideas? This is my first post, but I've been reading this forum for a while and am very impressed with all the knowlege and ingenuity here. Thanks for any help.

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post #2 of (permalink) Old 12-18-2000, 10:20 PM
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Re: command-trac question

There was a post this morning by YJ88 about the vac disconect on the YJ. It explaned what the different hoses were for and where they ran from. There may be some info their for you. My 88 also stopped disengaging but it just cured itself one day but now the dash 4x4 light won't come on.

'88 Sahara
post #3 of (permalink) Old 12-19-2000, 09:07 AM
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Re: command-trac question

Had that same problem last month. Turned out that I broke one of the vacuum lines inside the wire shield along the fender while installing my TFI coil. Couldn't figure it out until I pulled the shield and found where I cracked the line. Those lines are plastic, so they break/crack pretty easily. I fixed it by getting some small vacuum line and connecting it to the plastic lines where the break occured. Keep some extra vacuum line in your "spare parts" in case this happens again...Works really well.

Tommy B. in AZ -
More Guts than Brains.
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