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-   -   HOWTO: Retain 4wd light with passenger solid axle shaft upgrade (http://www.wranglerforum.com/f218/howto-retain-4wd-light-with-passenger-solid-axle-shaft-upgrade-138722.html)

darkproximity 02-10-2012 02:27 AM

HOWTO: Retain 4wd light with passenger solid axle shaft upgrade
 
So, you've gotten tired of fixing your Center Axle Disconnect (CAD) actuator motor, or you decided to just fix the problem before it was a problem and replaced it with a solid passenger axle shaft! Great! But now your 4WD light doesn't work. Well that sucks :(. If you have a junkyard nearby and can read this howto, you can fix this problem rather quickly and easily for just a few bucks! or if you want to go buy brand new stuff you can do it for about $50! I'll explain how the vacuum system for the CAD works so you'll get a pretty good understanding of the hows and whys.

The 4WD Indicator Light in the 91-95 YJ is the gauge closest to the drivers side in the center gauge cluster, to the left of the fuel gauge as pictured below. "4WD" With a graphic of the drivetrain will appear in the upper half of the gauge, the bottom half is not used.

http://i712.photobucket.com/albums/w...36e33dd824.jpg

In the 87-90 YJ the 4wd light is in the center of the dash along with the seat belt, parking brake, and high beams. Pictured below.

http://cdn.wranglerforum.com/attachm...1&d=1299444640

How it works:

To understand how this light becomes lit up when you shift your transfer case into 4wd, can be a bit tricky! It's not necessary to understand exactly how it works, but it will help you make sense of this workaround.

It all starts in the transfer case, the 4WD Vacuum Control Switch is located on top of the transfer case, if viewed from the back it is to the right of the shift linkage. You should see a rubber bushing with 4 tubes coming out.

Red is constant vacuum source to the transfer case
Yellow uses vacuum to engage the shift motor on the front axle CAD
Green uses vacuum to disengage the shift motor on the front axle CAD
Blue is release for the vacuum change, which will release vacuum in the unused hose

When the transfer case is placed in 4Hi, the 4WD Vacuum Contol Switch will send vacuum being produced by the intake manifold though the Red line, down the yellow line and engage the shift motor. Once the collar successfully engages, the indicator switch on the vacuum motor will relay to your 4WD light in the cab, to turn on.


Success! Now we somewhat sorta know how this works! So if you've replaced your 2 piece axle shaft with a solid shaft, regardless of how you dealt with closing off the CAD, even if you left everything hooked up as it was before, its advised you follow these directions to make sure you don't lose your 4wd light, or if you already ditched the vacuum lines, you've lost the 4wd light already!

What you need:

A TJ or 95+ XJ 4WD Indicator Lamp Switch:

http://images.oreillyauto.com/parts/...wd/fwd24_1.jpg
http://images.oreillyauto.com/parts/...wd/fwd24_3.jpg

OEM Replacement Part Number: J8134473
O'Reilly's Part Number: FWD24 (Link: BDW Band)
Autozone Part Number: SW2204 (Link: Duralast Brand)
Or just go grab one off the transfer case on the above mentioned vehicles at your local junk yard!

A specific pigtail connector to plug into the new 4WD Indicator Lamp Switch:

http://images.oreillyauto.com/parts/...wd/pt186_1.jpg

O'Reilly's Part Number: PT186 (Link: BWD Brand)
Autozone Part Number: 259 (Link: Duralast Brand)
Or again, snag it off the wiring harness connected to the switch you get at the junkyard!

Lets get started!

First lets assume you have already swapped out the shafts and taken care of the vacuum lines! You should still have the 2 pin pigtail that was connected to the old vacuum shift motor housing.

1. Cut the connector off the pigtail that used to be connected to the shift motor housing

2. Splice in new 2 pin pigtail (PN: PT186 / 259, see above) (Soldier and heat shrink is recommended)

3. Test fit the new 4WD Indicator Lamp Switch (PN: J8134473 / FWD24 / SW2204, see above) onto the new 2 pin pigtail.
Note: You may need to modify the 4WD Indicator Lamp Switch as it is meant for a plug that can only be inserted one way. It has a small protrusion inside the connector that may need removed so the switch will work.

4. Remove old Vacuum 4WD Vacuum Control Switch from transfer case (location noted above). Move the rubber gasket up off the switch and use 1-1/16" wrench or deep wall socket to unbolt.

5. Replace with new 4WD Indicator Lamp Switch using 7/8" wrench or deep wall socket, plug new 2 pin pigtail into switch. This will require you to relocate this portion of the wiring harness up and over the transmission back to the transfer case.

6. Before securing the wiring, check and make sure everything is working. Turn key to on position and make sure transfer case is in 2hi, then switch to 4hi, the light should now light up.

7. If you haven't already, Plug the vacuum source on the intake manifold with 1/8" vacuum plug

YJ Jeep Freak 02-10-2012 06:28 AM

Great walk through!
 
Hey thanks for the walk through. I have been wanting to take this on for a while. With this info with parts including part numbers, it should push me to get started on it. One question, just to make sure, the newer switch is still vacuum? If so, when testing 2wd going to 4wd you would need vehicle running? Thanks again. :thumb:

wvhillbilly 02-10-2012 11:12 AM

if you remove the 4 vacuum lines of the top of the trans it cant be vacuum used to turn the switch on can there? what in the trans makes the switch click over?

darkproximity 02-10-2012 12:52 PM

The newer switch doesn't use vacuum at all, there is a roller ball inside the switch which you can see in the photo above.. i believe the internal shifting mechanism pushes against the ball.. when that ball is pushed in it completes the circuit and thus the light turns on. you can test this out by unplugging the harness thats plugged into the CAD, and jumping it with a paperclip.. the light should stay on constantly until removed :)

YJ Jeep Freak 02-10-2012 01:23 PM

I thought it looked like a contact switch. Wasn't sure. So is there adjustment as far as how far you tighten the switch? Thanks again. 👍

darkproximity 02-10-2012 01:28 PM

nope i just snugged it down, works great.. though i went to pull and save in north spokane and was able to just grab a switch off an xj with the harness end.. i think it cost me a buck?

wvhillbilly 02-10-2012 01:51 PM

Thats what i figured but i didnt know if there was a contact in there or not.. awsome fix man def doin this soon great How TO!!!

darkproximity 02-10-2012 02:08 PM

Thanks! I just did it the other night, would've taken pics but i think i did an okay job explaining it.. plus it was dark out

darkproximity 02-10-2012 02:12 PM

The reason i decided to do this was i drove about 15 miles the other day, including freeway driving without realizing i left it in 4hi.. oops.. ive only ever left it in 4wd once but figured it out quickly when i had to make a sharp turn.. wont have the problem anymore :D

wvhillbilly 02-10-2012 02:49 PM

yeah i have did the same thing it sucks

farmer_74 02-10-2012 04:06 PM

Nice write-up :thumb:

darkproximity 02-10-2012 04:25 PM

Thanks :-)

If anyone ends up doing this post up your results and if you end up using an earlier xj like a 92, and it works let me know.. im pretty certain it will, the hex size might be different but it shouldn't matter as long as its the right thread pitch and length. Don't think new process would've changed it much throughout the years

YJ Jeep Freak 02-10-2012 11:40 PM

Did Pull N Save North have a few XJ's? I have never been there, but someone told me they charge to get in and then they take the charge off the price of what ever you found. Is that the way it works? :wavey:

darkproximity 02-11-2012 04:01 AM

Its 2 bucks to get in.. then they charge by part.. you dont get it taken off the cost of entry.. the north pull n save has more xjs than the valley right now too

Master4th 03-08-2012 07:45 PM

I completed the 4x4 shift motor mod today.


After I got it apart and began cleaning it for reinstall I noticed that my shift motor housing has no plug for a switch?!





I have a 1988 Wrangler, when I cleaned up the excess wires from my 350 install I probably cut the head off the 4x4 switch (Now I realize becuase I didn't see anywhere to attach it) and it is now in the Unused wire bungled hanging out of the fuse box.

I should be getting the parts for the above mod tomorrow, could anyone be so kind to tell me the wire colors for the 4wd light switch.

SRH92YJ 03-13-2012 03:35 PM

cool write up i'm gonna have to try this out

Dr. Venture 03-19-2012 09:27 PM

I switched to solid front axles, and just kept my vacuum engangement still connected. 4x4 light works. Fork internal does not touch the smaller diameter axle so all is well. I even have a write up thread. what controls the light inside is actually the fork actuator engaging in the fornt axle right side. New models after 95 light is controlled from the trans axle. All in all if your vacuum works fine, no matter what upgrade you do as long as you leave the front axle actuator connected just remove the innter engagmenet sprocket but leave the fork you'll be fine with th elight on.

here is my thread. http://www.wranglerforum.com/f8/93-y...es-132733.html

darkproximity 03-19-2012 10:04 PM

your method is still dependant on the vacuum system working correctly. Also the newer 96+ is controlled by the same switch on the transfer case that you would be changing to with this howto.

Dr. Venture 03-19-2012 10:20 PM

yeah but whats the big deal if the vacuum works correctly? just make sure its all secure and good then the light will work correctly right? i thought about the upgrade like this myself but figured F it...plus i was lazy after all that work.

darkproximity 03-19-2012 10:31 PM

Because the vacuum lines are one of the reasons for failure. Sure someone can do as you suggested but later down the line run into the issue of no longer having a 4wd light..

The whole point of this writeup is to get rid of the vacuum system entirely and go to the much less convoluted way its been done on every other jeep since the xj ditched the CAD besides the yj.

Dr. Venture 03-19-2012 10:50 PM

i hear ya, but with solid axles i mean once you throw the shifter into 4x4 light on or not its in 4x4....truth be told all i really did was cut the vacuum adapter down a lil to make it tighter fit on the transfer case. I was going to do this set up, and now i have a better idea of how to with this write up...thanks! if my vacuum ever gives me issues i'll consider though.

year1camaro 04-16-2012 11:53 AM

Love this info......! Thank you

darkproximity 04-16-2012 05:20 PM

Quote:

Originally Posted by year1camaro
Love this info......! Thank you

No problem, glad it helped!

jeff_in_rc 04-17-2012 01:07 PM

OK newbie questions here
 
I get where the "4wd vacume control switch" is on the transfer case.
I get where the "shift motor" is on the front axle.
I don't get where the "vacume motor" is with a 2 wire connector. :confused:

Sorry but I am new to Jeeps. :hide:

My stock YJ is having problems with vacume lines and I was thinking if I did this mod I would save myself some trouble down the road. That and I have an "always on" 4wd light.

I have also read somewhere here that I can remove the shift motor and "pin" it in place to keep the front axle in 4wd mode. Am I correct or am I full of it?

Thanks for any help you all can provide. :thumb:

jeff_in_rc 04-23-2012 10:21 AM

OK I found it!
 
While under the jeep for another reason I traced the vacume lines from the transfer case to the front axle and in between is the vacume motor. I proved it by disconnecting the wire and the 4WD light went out then re-connecting the wire and it came back on.

On to the new parts and pinning the front axle and I will be golden!

89FLIslander 05-07-2012 02:43 PM

Nice article. Very complete and informative BUT I still have a small problem. I recently had a Posi-Loc installed on my '89 Islander and the shop didn't run the wire from the Posi-Lok actuator unit to the "OEM Vacuum switch" to make the 4wd indicator on the dash work.

The instructions that came with the Posi-Lok state;

IF THERE IS NO ELECTRICAL SWITCH ON THE ORIGINAL COVER:
WITH ELECTRICAL SWITCH ON ORIGINAL COVER:
Cut off OEM terminal end, add #8 terminals to
wires; OE wires, either wire to either terminal
Make up 5 lead with #8 wire (supplied) and 1/4 lug
terminals and connect to upper cover mounting bolt
(ground)
Route another line up to OEM vacuum switch; cut
and splice to "OEM wire" with butt splice provided. On
some YJs the switch is under the battery tray. For XJ
applications, see Fig. 16.

Can anyone tell me where or what color the "OEM wire" is that I need to butt splice into?

Thanks to all!

jeff_in_rc 05-07-2012 03:43 PM

OK how about both where and what!
 
Quote:

Originally Posted by 89FLIslander (Post 2343770)
Nice article. Very complete and informative BUT I still have a small problem. I recently had a Posi-Loc installed on my '89 Islander and the shop didn't run the wire from the Posi-Lok actuator unit to the "OEM Vacuum switch" to make the 4wd indicator on the dash work.

The instructions that came with the Posi-Lok state;

IF THERE IS NO ELECTRICAL SWITCH ON THE ORIGINAL COVER:
WITH ELECTRICAL SWITCH ON ORIGINAL COVER:
Cut off OEM terminal end, add #8 terminals to
wires; OE wires, either wire to either terminal
Make up 5 lead with #8 wire (supplied) and 1/4 lug
terminals and connect to upper cover mounting bolt
(ground)
Route another line up to OEM vacuum switch; cut
and splice to "OEM wire" with butt splice provided. On
some YJs the switch is under the battery tray. For XJ
applications, see Fig. 16.

Can anyone tell me where or what color the "OEM wire" is that I need to butt splice into?

Thanks to all!

OK, just went out and looked at my 88, if you trace the vacume lines from the front axle towards the transfer case on the right side of the jeep you will see (at least on mine) a vacume line going to the firewall to a switch (mine is blue/white). One wire is grounded and the other is BLACK with a YELLOW stripe.

The BLACK with a YELLOW stripe is what you are looking for! :thumb:

89FLIslander 05-07-2012 04:23 PM

Seems like I'm bangin' my head against a wall (or the driveway) here. No blue/white vacuum line to be seen. No black/yellow striped wire either. Closest thing to it is a black and (possibly) yellow or pale green wire that is goes into a relay that is mounted on a bracket (between the battery and the fender). There are two relays mounted on that bracket. Sound close? Thank you for your reply!

89FLIslander 05-07-2012 04:35 PM

NEVER GIVE UP! Went back and looked again. Found a black/yellow wire (and another wire) coming out of a plug on the side of the transmission. It goes up to another plug which connects the two wires to two vacuum switches mounted in about the center of the firewall (over the end of the motor). Is that the right black/yellow wire? :banghead:

jeff_in_rc 05-07-2012 05:10 PM

Quote:

Originally Posted by 89FLIslander (Post 2344081)
NEVER GIVE UP! Went back and looked again. Found a black/yellow wire (and another wire) coming out of a plug on the side of the transmission. It goes up to another plug which connects the two wires to two vacuum switches mounted in about the center of the firewall (over the end of the motor). Is that the right black/yellow wire? :banghead:

On my 2.5 L I only have the one vacume switch, do you have the 4.0 L 6?

If you have an "always on 4WD light" try this, turn the key on, check the light, if it's on unplug the suspected connector, does the light go out? If yes plug it back in, does it come back on? If yes there you go!


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