I am new to jeep and I went to take my 90 yj out for the first time and I have no four wheel drive pretty disappointing . When I put it in four low my gearing changes for the rear but I have no drive in the front. I dont think my hubs are locking is there any way to lock them manually and does anyone know why this is happening? Thanks

very common problem, check vacuum actuator for front axle. many threads on this, i think one is sticky in the yj section

Just went through this myself.Ihad multiple issues.All the lines were melted at the switch in the transfer case.Fixd those.Then ended up not even having vacuum to the switch.Red line is constant vacuum to the switch.Make sure you have that first.If you have vacuum coming into the switch than you need vacuum coming out of it.Don't mind the blue line it just hangs out doing noth'n.Shift into 4wd and then pull the yellow lines off(double plug) the shift motor on the axle(pass side,disc shaped) and put your finger on there and see if you are getting vacuum.Let us know.

GO with posi-lock. I love mine

out of all the problems one can have with a jeep this is probably the only one i havent had yet lol lets hope it stays that way. anyways good luck with it.

is that the cable switch? i've been looking at that. you can have rwd low range to right?

Trust me.If that 5.00 piece of vacuum hose didn't fix mine,it was gett'n the posi-lok.Had my eye on one.I was just look'n for a reason.You can make your headaches dissapear for 200 bucks.Pretty sweet.If mine so much as looks at me wrong.It's gett'n it.

No it don't have the rwd low just 4wd high and low.

i checked for my lines for vacuum and they are good is there any other way of bypassing the actuator without putting on manual locking hubs?

Ok.you say you have vacuum?If that's true and you have vacuum at the shift motor than it sounds like your shift motor(acuator) is bad.You can install a posi-lok.It is a cable operated unit that fits in place of your actuator on the axle.About 200 bucks.Not a very hard install.All controlled by you inside the cab.

http://home.earthlink.net/~stevensch...h/cabledis.htm

Much much cheaper.Definitely build your own.

This is great info on the posi lock this is going to help me out a lot I will be putting it together this weekend. Hopefully everything will work out. Thanks for your help

Shift Motor Question

I found I didn't have 4wd when we were snowed in. I put off working on it until summer and then 2 more summers went by.
I didn't know there was supposed to be a light on the dash so troubleshooting was tricky.
The bottom line is this: Both vacuum lines going to the shift motor were eaten by battery acid, the diaphragm in the shift motor leaked and the switch on the transfer case was bad. Also, the new switch's "keyed" connector was of a different size and I had to grind it down to make the vacuum lines fit.
If it was just one problem, I think I could have solved it pretty quick but that's just not the way things work, is it?

Wait 'till you hear the gas tank story....

Here's my $1.50 fix and it took all of 15 minutes...

Here's the offending part:



I dissected it:



Everything inside looked fine, no wear on the fork anywhere. So I stuck the spring and the first c-clip on the shaft, wormed it thru the housing and put the other clips on.



Bob's your uncle, there is just enough movement to accommodate any binding but not enough to disengage the collar.

I did this back in September. I drive it on the street with zero issues and I've had it wheeling several times with no problems.

a savings og 65-220 $$$$$$$$$$$$$$$. good fix. do you remembe the spring lenght?

The spring I got at the hardware store was 2" un-compressed.

i had thought maybe a piece of all thread with nuts and washers. but i threw that out as binding might be a problem. the spring would take care of that. good on ya. mike

I am not finding the #1 softball size container under the battery only thing under my battery is the blower motor?

Post 14 diagram

I am having similar problems as well. I wish the pictures were still available. Ive been trying to study the diagrams on this site. Tomorrow I am going to attempt to check the vacuum.