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Moduhrater
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809 Posts
Discussion Starter #1 (Edited)
This thread is in addition to my Center Axle Disconnect Replacements thread. This thread is meant to give you a workaround when replacing your two piece axle shaft with solid xj/tj axle shafts.

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.



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.



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 the 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:




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:



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 still 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.

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

I will update this thread with more pictures at a later date.
 

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Premium Member
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660 Posts
Great writeup!
 

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Moduhrater
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809 Posts
Discussion Starter #3
Updated with correct wrench/socket sizes for removing old and installating new switches on the transfer case
Also you may be able to use earlier than 95 junkyard xj switches (92+) look for one without CAD. I will try to confirm this and update later.. but im 90% sure it will work
 

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King Thread De-Railer
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2,801 Posts
Updated with correct wrench/socket sizes for removing old and installating new switches on the transfer case
Also you may be able to use earlier than 95 junkyard xj switches (92+) look for one without CAD. I will try to confirm this and update later.. but im 90% sure it will work
they want a writeup on the durango steering box swap for the YJs your on it i don't do YJs :p
 

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Moduhrater
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809 Posts
Discussion Starter #5
I havent done the swap.. maybe ill do that soon..
 

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Junior Member
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9 Posts
I locked my cad out on an 89 and this will give me back the light, Thanks for a great write-up and including the antique early years.
 
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