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Just realized my vacum hosrs are cut and dont have the hands or patience to mess with it. How are Posi-loks? Will my 4x light come back on??
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Posi-lok
I have the Posi-lok unit on my 1989 YJ. The cable has served me well for about five years. and yes the 4wd light works. It not only allows 4wd, (locked f&r) but you can turn it off to use 3wd. (both rear and 1 front) this is handy maneuvering in tight spaces.
With the Posi-lok the front axle shifts properly and my previous vacuum problems have disappeared. (Motor now surprisingly runs smooth)
Here is a past post describing the 4wd vacuum system if that helps you to fix the stock set up.
To understand how the system works might help to repair it.
Once you engage the transfer case shifter into four wheel drive these processes take place. (89YJ) it should be similar on other YJ’s with the same set up.
On the dash is a light that tells you when you are in 4wd.
Under the battery (Passenger side) is a switch for the 4wd light (One wire to ground the other to the dash 4wd light). Note: The 4wd light has power with the key on, but lacks ground until this switch is activated.
The shift motor is where all of the vacuum hoses attach on the front axle. Which originate at the top of the transfer case.
From there to the drivers wheel (early Yj USA) is the long axle and to the passenger wheel is the short axle.
Inside the shift motor is a coupler that when engaged slides over and connects them both to create one passenger side axle.
On the shift motor there are three connections.
One vacuum line engages the coupler (which makes it slide over both axle ends), and at the same time the second sends vacuum to the switch under the battery to ground the 4wd dash light.
The third is to disengage the coupler and at that time the vacuum is cut off the dash light switch which disconnects the ground, which turns off the light.
Things that can be bad are.
1. Inside the shift motor, the coupler is broken or it isn't installed correctly)(I find installation is usually the problem)
2.The vacuum lines are incorrectly routed or broken (Note: the colored plastic lines are very brittle with age. One leak and it won't work)(The Jeep will also run ruff ie.vacuum leak)
3.The vacuum/light switch under the battery isn't grounded to the firewall correctly or it's broken (Usually it's loose and not grounded)
4. The dash light is not working (Bad bulb or wiring) (Usually it's the bulb)
Note: The wiring is simple. When vacuum is applied to the switch it connects the two wires inside and allows ground to the 4wd light (It lights up)
5. It just isn’t hooked up correctly or at all.
6. The transfer case shifter came loose or the linkage needs adjustment for full throw.
Look under the Jeep (Not running) have someone move the 4wd lever and see if it’s loose,(It will slide on the linkage shaft) unhooked, or needing adjustment.(Full forward and back, this usually happens with lifted Jeeps) -
Make it yourself if you feel confident, the Posi-Lok kit seems a bit overpriced to me. There are quite a few write ups on it out there on the net.I have a JeepComment
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Madison, thanks alot!! Lots of good infoComment
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