Using your existing relay box for adding electric accessories


Staff Member
Sep 28, 2015
Florence, AZ
This write-up was performed on an XJ, but the concept (and a lot of the diagrams) should be very similar to a TJ.

The motive is to use the existing fuse holder and existing relay holders in the Power Distribution Center (PDC).

I got no ABS, so the whole top row (as shown on the diagram) is empty in mine.

There's also plenty of fuse spaces.

Go get a PDC at the junkyard that matches yours.

Relays are gone but the boxes are everywhere.


Remove your positive terminal from the battery, and the feed to the PDC from it's main terminal.
There's 2 metal tabs to remove the PDC from the body (big screwdriver)
Then 6 tabs to remove the bottom cover.
That's all that's in mine, if you got a lot of options, power windows, power doors, all that, you probably are a little fuller in there.




Remove the cover from the bottom of the bus.
These are things you should start doing first on your junkyard PDC, so you get used to breaking the little tabs off, and realizing how you should have removed it without doing that.


So looking down through the main fuse bar, you can see the empty holes have no metal terminal in them, you need to get the little connectors out of the JY PDC and put them in yours.
I should have taken the other fuses out for this pic so you can see what I mean.
Take a picture of your fuses & relays so you know where to put them back...


This is the JY box, the bus (the main terminal in the PDC) has been removed. It's just plugged into every slot, so work it with a screwdriver out of there.


Remove the bus plugs, the little metal inserts.
There's little slots in the front that catches a tab on the metal part, then it slides right out the bottom.
The first one isn't coming out easy, but start cutting the junkyard box open if you have to and when you get the first one out look at the little catch on the side of the bus plug. You have to hit that from the front, through the slot in the main housing.
Plug them up from the bottom, into your PDC.


In both pictures I have the yellow fuse center plate in, but that has to come out to do all this, and if you break any of the little tabs, the yellow thing isn't going back in right.
So don't do that.

Also, look at the bus and the last fuse spot at the main terminal, where it plugs in is the opposite side, so consider that when you're putting your bus plugs in.


You need to get a good bit of the wiring pigtail when you get your junkyard box to reuse the wiring & connectors.
By now you've shredded your JY PDC.


Plug those into the bottom of yours.
There's different wire sizes, pay attention to that for what size relays you're going to use, which you would figure out using the first chart.
I was able to add 3 new fused hot leads, and will be taking them straight to a new relay bank.


Each row is independant of the box, and again with the little tabs that break super easy.
The yellow part comes off first, 2 tabs from the bottom.
Then the black part pushes through the bottom, with 2 tabs on each side of the top.
So I ditched the 2 large relay spots, for a row of the (4) 30a ones [4671168].
There's a little nub I had to chop off so the 4 bank fit where the 2 one was.



So since everything hot is right there, I'll do a ground trigger.


The 3 new hot leads are the 30s, tie each 85 to that to power the switch.


The yellow/brown/green are my 3 86s to the cabin, the big reds are my 87's.
I'm only using 1 for now, to do my driving lights, the other 2 are for future.



So here's the new arrangement. New bank of 4 across the top. Only 3 of those are wired up, only 1 of those is in use.


All I have to do is plug in fuses & relays, and these two are 30A feeds.


I also made an extra 60A fused lead with no relay, for a future inside relay box.
It's not hot until I plug a fuse in that last position.


Testing out my switch at the battery.
The brown is the one I'm using, the yellow and green will switch the future relays.


And finally...



May 7, 2017
Glendale, AZ, United States
Hey - thanks for this write-up. Yesterday I was having a weird problem with my TJ, and in the process I opened up my fuse box and noticed the end was "empty" where some relays (for things my Jeep doesn't have) were supposed to go. I'm gunna now have to look for one of the quad-relay holders (well, the whole box and harness) to slot in there in the future. I've got some LED pods that came with her that were wired up very improperly: Wired direct from the battery (no fuses), thru a small hole in the firewall (no grommet!) to the switches (no relays!). It was a fire waiting to happen, and once I noticed it, I unplugged it post-haste. What's scaring me now is how the after-market radio is wired in (I'm hoping they used a harness adapter, but after seeing the lights, I'm not so certain). I ultimately need to piggyback off the wiring there (or use a fuse tap from the inner box) to power/control a VFD clock from a Camry I picked up (the clock on the radio is too dim to see in the daytime).
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TJ Enthusiast
Supporting Member
Dec 23, 2019
Athens, Greece

I understand there is a bus bar under the Maxi Fuses, so they are powered up, but I would like to ask how are the mini fuses powered in this PDC ?