The "you already have a relay box" Relay Box

Wasn't sure if this was modified or OEM tech, but since I modified it I dumped this here. 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...

Thanks for this. I have been planning to use a WJ box but haven't been able to get them apart at the junkyard without breaking everything.

nice! always thought about doing this...but removing the PDC and messing with the connections on the back seemed like asking for something to get screwed up. Well done - nice and clean.

GREAT work! I did this for the fan override switch on my 98 but I am terrible at documenting my work. This is a beautiful wiring job. Should be a FAQ or sticky IMO.

oh snap - just realized this was you that did this writeup Tim. Nice!

kastein said:

GREAT work! I did this for the fan override switch on my 98 but I am terrible at documenting my work. This is a beautiful wiring job. Should be a FAQ or sticky IMO.

Click to expand...

Thanks. I had to go back and take the last posts worth of pics. You get in there doing something and forget about the camera...

Picked this up at the junkyard on lunch break to finalize everything.

good thinking!

Great write up and nice work.

deucestudios said:

Thanks. I had to go back and take the last posts worth of pics. You get in there doing something and forget about the camera...

Picked this up at the junkyard on lunch break to finalize everything.

Click to expand...

how hard is it to find that fog switch at the boneyard? i'd definitely like to have one, but as usual, like the tow hooks and factory skid plates, i have yet to see one

just grab another defrost switch and cut the hole out yourself. The back of that panel already has the opening template punched in it you just need to cut the facing. Do you really need the labels?

yeah i suppose you're right, but now that i know that the cutout is already there, that leaves me more space for other things in the panel on the other side (not sure what goes on that panel) i have nothing there, well, except for the CB radio mic holder, but im gonna relocate that eventually and get a fresh panel there for when i get lockers and other crap

Cancer there was 3 or 4 of them when I went.
There's a few types of double switch panels out there
fog light / rear defrost
trans power-comfort / rear wiper
extended idle / rear wiper

Also, some comanches have a double square blank panel there you could easily cut for two switches...

edit...nevermind...

Thanks for the write-up, I've been planning on a new PDC from some other vehicle to dedicate for all my add-ons. It's pretty hard to find a PDC with a lot of common, straightforward relays and fuses. From what I've seen of ZJ PDC's they've got a lot of standard relays but the last salvage yard I went to wanted $75 bucks for one. Screw that noise :banghead:

I did some searching, but wasn't really able to find out. Does anyone know the specs on the smaller Siemens relays (their current rating on the load side)? The PDC layouts do differ from years to years, The one on my 99 has four of the larger Bosh style relays, and four of the Siemens. The one from my 2000 is like your was originally with two Bosh, and eight Siemens.

the micro-ISO ones? I believe most of them are rated for 30 or 40 amps, but some may be 20s.

Yeah the mico-ISO ones. I found out they're several manufactures of them, and that the number on top is the Chry part number, but that was all I could find.

The FSM doesn't put an amperage to them anywhere I've seen, only the fuse ratings.
This link has the most info I've ever found on them.
http://pewa.panasonic.com/assets/pcsd/catalog/cm-catalog.pdf

It lists it as 35/20A, I think they can open more than they can close, or something like that.
At 12v, math says a pair of 55w daylighters pull just over 9A.
If I get curious enough I'll throw a clamp on them.

But... If you're gonna load up a circuit, go with the bigger relays. Do the opposite of the swap I did and add a big bank to yours, because I know I've seen a mini ISO relay (the other real common slightly bigger ones) that said 70A on it.