My 4 wheel drive is not engaging! - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 05-26-2010, 09:12 AM   #1
Jeeper
 
zacharytyoung's Avatar
 
Join Date: May 2010
Location: Norfolk, VA
Posts: 45
My 4 wheel drive is not engaging!

For some reason on my 1989 yj my 4 wheel drive is not engaging. When i put it in low 4 wheel drive, low gears kick in but not the 4 wheel drive. A freind of mine said that it may be a fluid that has leaked out of it and that maybe the reason. Im not sure but when i first bought it the 4 wheel drive did work and there was a little leak of something that did not have a smell, i know a substance was leaking from the jeep but could never figure out what it was. Finaly the leak stopped, and i went one day to engage my 4 wheel drive and it didnt work. Could the leak be what my friend was talking about or is there another reason?

zacharytyoung is offline   Quote Quick Reply
Old 05-26-2010, 09:25 AM   #2
Hacks off Parts while Lit
 
whitebuffalo's Avatar
 
Join Date: May 2005
Location: The Sandhills of South Texas
Posts: 2,290
no. it is most likely (almost certainly) the CAD on the front axle. it is a vacuum actuator to lock the passenger side shaft in. verify the vacuum lines are good to it (they come from the t case). if they are good, remove the CAD and check it out. you can replace it with a cable actuated one or repair it. usually, it is the diaphragm that goes bad, but on occasion the fork will crack.

easiest way to check it out is remove the CAD and let it hang. then, with the jeep running, shift back and forth from 4wd to 2wd and see if the fork is moving back and forth.

__________________
'90 YJ, ford 8.8, SOA, lincoln front, aussie rear, 4.88s, swampers.
whitebuffalo is offline   Quote Quick Reply
Old 05-26-2010, 09:41 AM   #3
Jeeper
 
flatline's Avatar
 
Join Date: May 2010
Location: pinole ca.
Posts: 680
Images: 3
how did you know it wasn't working? are you going by the light on the dash?
flatline is offline   Quote Quick Reply
Old 05-26-2010, 10:32 AM   #4
Jeeper
 
zacharytyoung's Avatar
 
Join Date: May 2010
Location: Norfolk, VA
Posts: 45
No im not going by the light on the dash, the dash light sensers are all jacked up im in the prcess of rewiring, something im acctually good at, but the way i can tell it was working in the irst places is i made sharp turns on concrete and it made the sound of the front tires grabbing, now it wont make that sounds of the tires grabbing. o and i got stuck in a pit and try to engage the 4wheel drive an the front tires wouldnt work at all.
zacharytyoung is offline   Quote Quick Reply
Old 05-26-2010, 11:30 AM   #5
Jeeper
 
flatline's Avatar
 
Join Date: May 2010
Location: pinole ca.
Posts: 680
Images: 3
just asking, not trying to be a smart ass. the CAD is normally the problem with YJ's. easy thing to check first is vacuum to the cad, then cad. if all that works,check that you haven't broke an axle. then is the transfer case working, only thing that drives the front drive line is a chain.
flatline is offline   Quote Quick Reply
Old 05-26-2010, 11:45 AM   #6
Jeeper
 
toshpate's Avatar
 
Join Date: Feb 2010
Location: Oklahoma
Posts: 19,285
Images: 4
Send a message via AIM to toshpate Send a message via Yahoo to toshpate Send a message via Skype™ to toshpate
my vacuum lines actually come out..make sure they are plugged in, mine didnt work either and a line had come loose, pluggedit in an abra cadabra it worked.. hate the vacuum stuff grrr
__________________

GOOOOOOOOOO POKES!!!!!!
toshpate is offline   Quote Quick Reply
Old 12-20-2013, 09:28 PM   #7
Newb
 
Join Date: Sep 2013
Location: arizona
Posts: 2
does some one have a good diagram of the true vacuum lines and exactly where they belong. My 89 jeep yj differential locks in but won't engage front wheels. no dash light either lighting up.
jepptone is offline   Quote Quick Reply
Old 02-09-2014, 09:24 PM   #8
Jeeper
 
Join Date: Jan 2014
Posts: 15
I agree, does anyone have a good diagram of the vacuum line setup / connections from the T.C. to the front diff?
M48a3 is offline   Quote Quick Reply
Old 02-10-2014, 04:54 AM   #9
Jeeper
 
90DesertTanYJ's Avatar
 
Join Date: Jul 2012
Location: JAX, FL
Posts: 635
No diagram but there is one in the FSM. In a nut shell, vacuum comes from the engine, usually on the same line as the distributor. This goes to a switch on the transfer case. When you shift to 4wd, the switch sends vac to the CAD which couples your axles together, The CAD sends vac to the 4wd switch on the firewall which in turn closes the ground to the 4wd light. When you shift out, the vac is relieved by anothe vac line that goes also to the firewall. Its one that has a cane bend with nothing else.

Any of the switches, vac lines, the CAD motor could be bad. You could trace the vac lines with a vac gauge, checking all the functions.

Honestly its probly better to lock your CAD fork over or get a Cherokee/TJ one piece axle and TC switch. and be done with the CAD altogether. Check the stickies at the top for more info on how to do this easy mod.
90DesertTanYJ is offline   Quote Quick Reply
Old 02-11-2014, 08:30 PM   #10
Jeeper
 
vmaxaholic's Avatar
 
Join Date: Mar 2013
Location: Avon, CT
Posts: 51
I could write several paragraphs on how AWESOME the posi lock upgrade is. I've already written several in the last few days for other YJ owners with the same and/or similar problems. My issue was very similar. 4wd would sometimes engage, sometimes not...even if the light came on, sometimes still no 4wd. I installed the posi lock upgrade this past weekend and when I was finished, I wanted to kick my own ass for waiting as long as I did to do this. Now there is NO question about 4wd. I engage the t case, pull the cable and BAM!!! Instant, undeniable 4 wheel drive. Quadratech has them for $159. I got mine on ebay for $98 plus $12 shipping. Another guy on this forum said he got his shipped for $87 from Amazon. F*#k the CAD and the damn vacuum lines!!!! Do yourself a favor, and get the upgrade. This, of course, is assuming that your axle is good and the t case & linkage are all functioning properly.
vmaxaholic is offline   Quote Quick Reply
Old 02-16-2014, 05:44 AM   #11
Jeeper
 
Join Date: Sep 2013
Posts: 51
There is a way to delete the need for those vacuum lines with a couple of washers in the actuator. Look into that and delete those vacuum lines
__________________
1987 Jeep YJ 4.2l I6 - 33x12.5r15 BFG MT KM1, 3.5" Black Diamond Springs, 2" shackle lift,Nutter bypass, Vacuum delete, JB Conversions SS SYE, Magnaflow 40,
BUILT NOT BOUGHT X Flexy and I Know It!
DigitalDisciple is offline   Quote Quick Reply
Old 02-16-2014, 05:46 AM   #12
Jeeper
 
Join Date: Sep 2013
Posts: 51

__________________
1987 Jeep YJ 4.2l I6 - 33x12.5r15 BFG MT KM1, 3.5" Black Diamond Springs, 2" shackle lift,Nutter bypass, Vacuum delete, JB Conversions SS SYE, Magnaflow 40,
BUILT NOT BOUGHT X Flexy and I Know It!
DigitalDisciple is offline   Quote Quick Reply
Reply

Tags
no 4wheel drive

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
stuck in 4 wheel drive bayareamark TJ Tech Forum 4 05-10-2010 11:41 PM
how fast in 4 wheel drive bck4more YJ General Discussion Forum 2 05-06-2010 08:43 PM
Front wheel drive f-450 lost Off-Topic 7 02-15-2008 08:31 PM
Need help stuck in 4 wheel drive ? clutch269 TJ Tech Forum 2 02-12-2008 05:04 PM
Four Wheel Drive Problem xAuroNx YJ General Discussion Forum 6 09-16-2005 08:03 PM



» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 06:36 AM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC