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post #1 of (permalink) Old 03-05-2001, 03:14 PM
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4wd light on constantly

I just finished installing a weber carb in my YJ. Before the install the 4wd lite did not work(the 4wd worked fine). Now the 4wd lite is on constantly wether you are in 4wd or not. Anybody have any ideas on where to start looking for the problem.
Thanks Ed
89 YJ 4.2 tf999

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post #2 of (permalink) Old 03-05-2001, 04:27 PM
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Re: 4wd light on constantly

The light on my 88 is controled by a switch on the firewall just beside the battery. A vacuum line comes to this from the front axle. When its shifted into 4wd, vacuum is sent to the fork on the axle from the transfercase and from the axle to this switch. Can only assume you hooked up this vac line to the new carb by mistake. Check where all the vac hoses go to and hopefully you'll find the problem. This hose must have been disconnected before you started swapping the carb or the light would have worked before.

'88 Sahara, 4.2, auto.
post #3 of (permalink) Old 03-05-2001, 05:05 PM
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Re: 4wd light on constantly

Check out this diagram that I've attached. It is from an 88 YJ with a 258 and 5spd. It might help with identifying what goes where.


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post #4 of (permalink) Old 03-05-2001, 06:16 PM
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Re: 4wd light on constantly

Just to be sure, test to see if the front axle is unlocked while the t'case is in the 2wd mode. Lift the front passenger tire off the ground and try to spin it by hand. If it spins then the axle is unlocked and the shift collar is in the 2wd position.

If it spins and the light is on, then you have a vac line connected wrong somewhere. Refer to Bryan's diagram and Good luck!![img]/wwwthreads_images/icons/smile.gif[/img]

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post #5 of (permalink) Old 03-05-2001, 07:08 PM
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Re: 4wd light on constantly

Thanks for the input. The vac lines are hooked the same as the diagram. I am going to check to see if the axle is disconnected in the morning. One thing I didn't mention before was that the light would just come on out of the blue on a rare occasion. Don't know if that makes a difference. Any other possibilities ( the switch on the firewall bad etc.)

89 YJ 4.2 weber tf999

post #6 of (permalink) Old 03-12-2001, 12:12 AM
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Re: 4wd light on constantly

I,m eating my words. Finally replaced the switch for the 4x4 light. Put her into 4hi and the light came on for the first time in a year. Now it won't go off. Just checked the vacuum at the axle with it in 2wd and 4wd and I'm only getting vacuum in the yellow line. In the diagram from beee240, which line is 2wd and which is 4wd yellow or green? Looks like I'm buying a new t-case switch tomorrow but I'm trying to find out if my axle is locked now or not. If it is, it has been for months and that would explain the crappy milage.

'88 Sahara, 4.2, auto.
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