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Discussion Starter · #1 ·


This is my attempt to document what I did to convert my Laser from the standard Daytona '88 SMEC wiring harness, with fusible links, to a PDC, or PDM as some like to call them.



This writeup has taken me over a month to put together, and has grown to be much larger than I planned. I will post it in sections, so please be patient. I have multiple photos, schematics, and drawings, which should make it pretty simple. Please hold off on questions, until I finish, so that the main part stays intact.

If you haven't already read it, here is the post that inspired me to do my first one:
http://www.turbododge.com/forums/f4/f21/341999-how-convert-your-fusible-links-relays.html

It has good information, but not many pics, or schematics. I had a hard time understanding what it was trying to show. It used a PDC from an early '90s LeBaron. The problem is that finding PDC’s, from early 90’s LeBarons, and Daytonas, is getting harder and harder.

I decided to find a more common alternative. Fortunately, Chrysler bought out Jeep and used the same LeBaron PDC in their ’94 & 95 Cherokees. There are a lot more Cherokees than LeBarons, in junkyards, so they should be much easier to find.

Jeeps also used a slightly larger PDC, from ’93 thru the early 2000’s. Again, I found mine in Cherokees, but other Jeep models probably used the same one.



So far, I have used both sizes and found that the smaller one better fits our needs. The larger one has room for more fuses and relays, but you probably will never come close to using them all.
 

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Discussion Starter · #2 ·
You will also need a good wiring schematic for your vehicle. Look on eBay for the proper shop manual, as they have gotten pretty inexpensive.

When you go to the junkyard, you will want to buy 2 Jeep PDCs, and cut the wiring at least a foot from the PDC, or at least as far as you can. The mounting bracket only has 3 bolts, with 10mm hex heads, so grab it too.

It shouldn’t take you more than 15 minutes to cut the wires and unbolt the PDCs. Also, load them up with fuses and relays, because they will cost less now, than buying new ones later.

Here’s the list of fuses and relays that I used, but get some spares, as well.
4 - Relays, Large
2 - Fuse, Large, 60A
4 - Fuse, Large, 50A
2 - Fuse, Large, 40A
3 - Fuse, Large, 30A
1 – Fuse, Large, 20A
2 – PDC, Jeep, 1993 – 2000

You should be able to get everything for under $50. One thing to note, I grabbed about 3 ft of wiring and starter cable, and the yard considered it a harness. They tried to charge another $15 for it. I passed on it and decided to buy a new positive battery cable, instead, just out of principle. Just something to be aware of.

If you can weld, you can modify the mounting bracket to better fit your car’s location. That way, the PDC will easily clip in and out, using the factory mounting tabs.



This shows the rear of the larger Cherokee PDC. All of the years will show 743A, but the last letter designates what options it comes with. Again, it isn’t that important, as long as you get at least 2 large relay bays. Also, be sure to get the small cover, at the top of the pic, which covers the input power cable.

This is a pic of 2 different Jeep PDC’s. The only difference is the size of the center relay bays and how many fuses were installed.


This is what I will show you how to build. It should give you enough info to be able to modify it for whatever you decide you need.
 

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Discussion Starter · #3 ·
OK, time to start disassembly. Start by prying the back cover off. There are 3 tabs on each side.


Once you have the covers off, you end up with this mess. Don't worry, most of it will not be needed.


Remove the yellow plastic retainers, by using small screwdrivers, to release the locking tabs, and pulling them up.


The section for the mini fuses has locking tabs on the outer corners.


Flip the PDC over and remove the plastic piece that covers the metal distribution plate.


Use a large screwdriver to separate the plastic plate, leaving the metal plate in place.


Then pry the metal plate from the female terminals.


With the metal plate removed, you can see the terminals, attached to the wires, which we will be removing. Two of the wires run through the plates, so you will have to pull their terminal out before you can free the plate.


At this point, don’t worry about how the wires were positioned. We will cover it later, with schematics.
 

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Discussion Starter · #4 ·
The next step is to remove all of the wiring. You can leave the terminals that the metal plate goes into. There will be some empty sockets, which is one reason you will want 2 PDCs.


There is a trick to getting the larger terminals out. They are actually retained by two locking tabs. One is a metal tab that you need to press into the terminal, so that it won’t catch on the plastic housing. Press it flat and you can later bend it back out.


The other tab is plastic. Be careful, as you pull it clear, or it will break. Keep in mind that it is 20 year old plastic, so it will be brittle. If you break a tab, don’t worry, because just the one metal tang, on the terminal, will be enough to do the job.


After pushing the tab, away from the metal terminal, the terminal will push downward and out. If you have to force it, you still have a locked tab. The terminal should almost fall out. Remember, you only need to remove the terminals that have wires attached.


Now we move to the relay terminals. You need to remove them all, and probably won’t be reusing them, since your car’s old relay wires will snap right into the PDC relay terminal sockets. Even though they look different, in this pic, the large relay metal terminals are the same as the mini-relay terminals.


Again, the plastic tabs may be brittle, and break off. It's not a big deal, as you can use epoxy, or hot melt glue, to lock them in.

You can now remove the relay bays. There are tabs that hold the relay socket trays in place. Press the tabs inward and push the relay socket tray downward and out. It should slide easily, so don’t force it.




Finish removing the wires and terminals from the mini-fuse section and separate them by terminal size and wire gauge. You will end up with more than these.
 

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Discussion Starter · #5 ·
Now that you have stripped the PDCs, it's time to discuss how one will be configured. I decided that the easiest way to keep things organized is to number each terminal.

The dark center area represents the solid metal plate that distributes +12v power to the terminals. The battery cable bolts to it, outside the PDC, instead of to your old harness. I suggest getting a new 6 gauge, or thicker, red battery cable, that already has the proper terminals on both ends, to connect the positive battery terminal to the PDC.

This drawing is looking down, onto the PDC, as you would see it on the car, with the cover removed.


From this point on, when something is numbered, these are the locations being referred to.

This shows the original relay layout and where the fusible links are located, in my Daytona.


One thing that helps to make this project easier is that all of the terminals, that plug onto these relays, will plug directly into the PDC relay bays as long as their wires are long enough. If not, you can just cut the wires and solder in enough to make them fit.

This shows the wires, and their thickness, along with where they will end up connecting. I did it this way because it allowed the labeling, on the PDC cover, to match most of my wiring. Don’t get hung up on the color of the wiring, since you might not have the same colors. Just keep the gauge thicknesses the same, so that you don’t fry a wire with too much current.


Wires 9 & 13 are not needed, so you don’t really need to install them, but it’s easier to do it now, than later.
I used wire 15 to power my underhood LEDs using a mini fuse. You can populate any of the unused terminals for anything you like.
Wires 12 & 14 are for the alternator. Each one can handle 60A, so we will connect them in parallel, allowing us to run up to a 120A alternator. These joined 10 gauge wires will connect to the existing 6 gauge wire coming from the alternator.
 

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Discussion Starter · #6 ·
Moving on, we finally get to the schematics, which probably scare most people. Don't worry, as long as you have the correct schematic for your car, you will be fine. Our cars use pretty similar wiring, except for the coloring.


Coming from the left is the +12v battery cable that supplies the fusible links. You could connect it to the PDC supply, but it's better to just buy a new one that has the proper female terminal. Again, 6 gauge should be OK, but anything thicker would just be better.

This is the same schematic with the fusible links cut out. We'll cover it in more detail, later on.


The fusible links are color coded, to show how much current they are rated for. We are just replacing the fusible links with fuses. It's really that simple. The hardest part is getting at the links, as the harness may be tough to access, with the engine in the way. My car wasn't bad, but the Lasers and Daytonas have bigger engine bays.

This shows the battery supply schematic.


From the left, is the 6 gauge cable that goes to the starter. It went to the + battery terminal, but you can connect it to the PDC supply terminal, if you put a female connector on it.

The Hazzar/Flasher wire used a 2 pin connector. You can cut the connector and fusible link away and connect it to the PDC #10 wire.

The other + battery cable used the 2 piece connector. You can reuse it, or replace it with a solid red battery cable, to supply +12v to the PDC.

The Rear Defogger wire will go to the #8 PDC wire, which should be 12 gauge.
 

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Discussion Starter · #7 · (Edited)
Hopefully, I am organizing this so that it is easy to follow. I keep going back and forth as to the order to show things.

I guess now would be a good time to discuss the fusible links. Basically, they are just wires that act like fuses. Their thickness determines their current rating. We can ID them by their colors. There is a good explaination of them on the miniMopar site:
http://www.minimopar.net/electrical-links.html

This schematic is the same one you saw earlier, on pg 4, with the fusible links removed.


Starting from the left, is the wire that goes to the starter relay, on pg 5. Instead of using the wire that ran to the relay, you can now just use a 12G wire, from terminal #4 to terminal #31. You should be able to find one in your stack of wires. If not, just solder ones with the proper connectors. This will replace the wire that came from the fusible link to the old Starter relay.

Next is the 6G wire coming from the alternator. This shows where to cut the FL away from the splice end.


You will connect it to both 10G wires from #12 & 14. The alternator wire has the white QD connector, so you can unplug it and work away from the car. I connected my 3 wires by using a copper sleeve, just larger than the 3 bare wire ends. I mixed in solid solder, then crimped them together, after which I hit them with a torch and added more solder. They will never come apart. Obviously, you will want to add heat shrink tubing over all of your bare connections.

For the Radiator Fan relay, you will run a 14G wire from #7 to #41. This replaces the wire that came from the fusible link to the old Radiator Fan relay.

The ignition switch is supplied by two different fusible links. Even though both wires are 12G, they were connected to FL's with different current ratings. It does matter which wire goes to which size fuse. If you look at the original pg 4 schematic, you will see that wire J10 is connected to an 18G gray fusible link. That corresponds to a 50A fuse.
The other wire, J1, connected to a 20G orange FL. That corresponds to a 40A fuse. Therefore, you will connect J10 to a 12G wire from #1, and J1 will connect to a 12G wire from #3.

The 16G SMEC wire now connects to wire #6, with a 16G wire. I used a 12G, but anything 16G, or thicker, will do.

The Auto Shutdown relay will now be powered by a 14G wire running from #11 to #46. This replaces the J1 wire that ran from the FL to the ASD relay.

The 12G wire, for the Lights & Horn, will now go to a 12G wire from #5.

Hopefully, this now makes a lot more sense. Again, we are just replacing the FLs with fuses that can handle the same current as what the FLs were rated for.
 

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Discussion Starter · #8 ·
Once I figured out where all of the wires were supposed to go, the hardest part was removing the individual wires from the relay sockets. I will use pictures, to try to show how, but you will probably have to do some figuring out, on your own. If anyone wants to share their methods, feel free to add your suggestions.

If you can't get your connectors out of the relay sockets, you can just cut the wires and splice them to PDC wires that fit the PDC relay sockets. It's just more work for you, when plugging them in is so easy. This is my AC relay, but the socket is the same as the others, except the ASD relay.


To remove the individual terminals, you first need to remove the yellow retaining clip. I can't remember, but there may be more than one, in some sockets. Just push in the barbs, on the ends, and push the clip up and out.


Then you can use a small screwdriver to unlock the terminals, like you did in the PDC.


We will cover the ASD relay, a little later.

On to the Radiator Fan relay wiring. If you have a car with AC, you will want to skip this schematic and go down to the next one, as the wiring is more involved.


Just remove the terminals and plug them into the PDC sockets. Note that you will not need wire #41, because it has already been replaced in the PDC.

If you have AC, you will want to refer to this schematic. If not, you are done with this post. The AC relay and the Radiator Fan relay share some wiring.


Note that terminal #41 has 2 wires going into it, labelled C26. One is from #7, which we ran earlier. The other is from #52. You can probably find wires, from the PDC collection, that will do this. If not, just splice them together.

There are also wires from #45, labelled C25, that connect to #51 and the Radiator Fan connector. You should be able to reuse the originals, once you remove them from the old harness.
 

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Discussion Starter · #9 ·
Next up is the Starter relay.


You will not be reusing #31, as you have already replaced it in the PSD.

On to the ASD relay. I don't know why this was so hard to remove the terminals from, but I ended up just cutting the wires and splicing them. I will show how I attempted to remove them, but you can decide if you want to try.

This is how the ASD socket looks like.


There is a release tab that goes through the entire socket.


You need to get it out of the socket.


This is the dumbest setup I have encountered!

We're getting near the end. This is the ASD schematic.


Wire #46 has already been replaced in the PDC, and connects to #11. Connect the other 3 to the PDC terminals.

If you have any loose terminals, you can lock them in place by filling the cavities with epoxy, or hot melt glue, like I am doing in this pic. I admit that the wiring doesn't look very pretty, but keep in mind that I have cut an spliced this harness several times over the last 8 years. I wish that I had know how to do this way back then, as it would have been so much easier, and cheaper than replacing the old relays, during troubleshooting.

My PDC works fine, so my work was correct, but if you find that I have made any mistakes, please feel free to correct me. I put this documentation together long after I did the project. I have reviewed it several times, but there's always a chance for mistake.

Hopefully, this will convince others to make the conversion. It really isn't that hard to do, if you can get at the harness. I plan to do another one for my Daytona, using the smaller Jeep PDC, but that project won't be until next winter, and I will be using an '87 harness, which has the logic module inside the car, and a separate power module.
 

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Discussion Starter · #10 ·
Here are some more pics of the finished PDC. These were taken at different stages, out of sequence.





This shows how the battery cable connects.


Make sure you use the plastic cover, since the cable lies close to the fender.


You can see the modified bracket, below the PDC.


You can see the white terminal strip between the PDC and the strut tower. I connected the mini-fuse wire #15 to one of its terminals. This feeds the switch to the underhood LEDs.


 

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Discussion Starter · #12 ·
I was looking through all the information on how to do this and was going to tackle the job next time I go home. This is a great write-up and I'm glad you did it because it simplifies a lot of things for me when the time comes.
To me, it's like the serpentine belt setup. Once you do one, you'll never want the original setup again.
 

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Here are some more pics of the finished PDC. These were taken at different stages, out of sequence.

IIRC, the A/C clutch cycling relay has some de-spiking or clamping diodes built into the relay. I can't see for sure what all of your relay numbers are. Did you consider the added diodes? Did you add them to the wire harness?

Great write-up again!!
 

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Discussion Starter · #14 ·
IIRC, the A/C clutch cycling relay has some de-spiking or clamping diodes built into the relay. I can't see for sure what all of your relay numbers are. Did you consider the added diodes? Did you add them to the wire harness?



The original wire N13 contains the diode, going to the SMEC. It connects to #54, so it would still have the diode.
 

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IIRC, the A/C clutch cycling relay has some de-spiking or clamping diodes built into the relay. I can't see for sure what all of your relay numbers are. Did you consider the added diodes? Did you add them to the wire harness?



The original wire N13 contains the diode, going to the SMEC. It connects to #54, so it would still have the diode.
The N13 wire/diode protects the ECM.

The diode inside the relay protects the relay contacts from excessive erosion when the A/C clutch is de-energised and the magnetic field collapses. A large spark can be generated as the A/C clutch coil collapses.
 

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Discussion Starter · #16 ·
The N13 wire/diode protects the ECM.

The diode inside the relay protects the relay contacts from excessive erosion when the A/C clutch is de-energised and the magnetic field collapses. A large spark can be generated as the A/C clutch coil collapses.
As far as I can tell, the stock 04848879AA and 56006709 relays are OK to use with the AC circuit and everything else. Does anyone know what P/N's to use for each circuit?



 

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This should be a sticky! Excellent job. I've been thinking about trying this in my TII rampage. Your write up is much more detailed the the sticky'd one. No offense to OP. He brought this mod into the realm of doable. I just have to get to the JY and measure the jeep PDC. I may be able to squeeze a 2" wide box between intake and shock tower.
Thanks for your detailed work!
 

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Discussion Starter · #18 ·
This should be a sticky! Excellent job. I've been thinking about trying this in my TII rampage. Your write up is much more detailed the the sticky'd one. No offense to OP. He brought this mod into the realm of doable. I just have to get to the JY and measure the jeep PDC. I may be able to squeeze a 2" wide box between intake and shock tower.
Thanks for your detailed work!
If you do the conversion, let me know if you find any issues with my write up. It's hard to remember everything, because you are trying to remember what you did. My fear is that I'll forget something that will end up confusing someone.
 

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Discussion Starter · #20 ·
This is great but hard to follow without pictures. Any chance you'd be willing to repost your pictures somewhere other than PhotoBucket to get them working again?
PhotoBucket must have just done this, as it was working last week. I'll try to reset my settings. It would be nice if we could put the pics on this server, so we wouldn't keep losing them when photo companies go away.
 
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