robbynne

PART 2

At this point, you are ready to begin dis-assembly of the PDC. Move the PDC to a well lit and padded work area (your formal dining room table is fine). Since you will be dealing with lots of electrical contacts it is prudent to clean the accumulation of dust off all surfaces of the PDC. Compressed air, aerosol electrical contact cleaner, soft brushes and cotton swabs are all helpful. It is not necessary to remove any of the fuses or relays from the PDC.

9. The PDC assembly is a sealed unit secured by three (3) plastic bosses which must be ground away to separate the PDC from its housing and gain access to the printed circuit board (PCB). The locations of the bosses are shown in the first photo.

http://byfiles.storage.live.com/y1pi...xrW4dWcjemKCLQ

I used a battery powered Dremel with an end cutting milling tip (#194) ( 1/8" dia.) to grind off the bosses flush with the bottom of the recess in which they are located. Then I ground through the bottom of the recess approximately 1/16" to the top of the plastic post below on which the PDC sits and to which is is fastened via the boss. I also drilled through the posts from the bottom side of the PDC with a 3/32" dia. drill. This makes it a bit easier to ascertain when you have ground the boss free of the PDC. These three (3) holes will be filled later with structural epoxy or sheet metal screws to resecure the PDC to its housing. If you insert a popsicle stick (a small flat bladed screwdriver or similar object works equally well) between the housing and the recess where the boss was located and exert a bit of pressure you should be able to see the PDC move (slightly) freely from the post itself. If you don't then you probably have not ground enough of the boss away. When you are satisfied that the bosses securing the PDC to its housing have been removed, you are ready to separate the two halves.

There are undoubtedly alternate methods by which to remove the plastic bosses holding the PDC top half to its housing. Whatever means one employs, the objective is to remove the bosses without destroying the posts of the bottom housing on which the top half of the PDC rests.

10. Remove the B+ terminal post from its cavity by depressing the two (2) plastic tabs located in the recess of the bottom half of the PDC (under the post) and pressing down on the top of the post simultaneously. The terminal post should drop out of the recess. See second photo.

http://byfiles.storage.live.com/y1pP...FnKxooV0ayWvgQ

11. The PDC is further secured to its housing via seven (7) friction fit plastic tabs/recesses located along the perimeter of the PDC assembly as shown by the yellow dots in the third photo. I used a metallic silver Sharpie permanent marker to identify the locations of the tabs/recesses on the PDC case. If you look closely on the edge of the case, you will see a faint embossing approximately 5/16" wide where each tab/recess is located.

http://byfiles.storage.live.com/y1p0...bGMSOy0AYyiaag

It is IMPERATIVE to free the PDC from its housing GRADUALLY and EVENLY. All of the terminal pins located in the housings to which the electrical connectors attached (on the bottom of the PDC) are attached to the PDC's printed circuit board. These terminal pins must not be bent as they move through the holes in the PDC housing.

Disengage the metal bus bar (where the B+ terminal stud was located) from its cavity by inserting a small flat bladed screwdriver between the metal tab and the plastic housing in the recess on the bottom side of the PDC (see second photo). Slip a toothpick or small shim between the bottom of the buss bar and the housing to prevent the metal tab from re-engaging while you are separating the PDC from its housing.

12. I used popsicle sticks (or similar shims) wedged between the PDC and its case adjacent to the seven (7) tab/recess locations to keep them from re-engaging while I pried the PDC from its housing.

Start with the two (2) tab/recess locations on the case nearest where the FCM was located. I used a small (1/8" wide) flat bladed screwdriver wedged between the PDC and its housing (at each tab/recess location) to gently pry the PDC free. Remember, you are pulling all of those electrical terminal pins up through the bottom of the case, so there is lots of friction. There is also a lot of resistance where the FCM connector is located. Work your way around all seven (7) tab/recess locations until they are free. Then gradually and evenly work your way around prying the PDC straight up from its housing. When it is nearly completely free, you will see the edge of the green printed circuit board which is the very bottom of the (top half) of the PDC. Do NOT use the screwdriver to pry between the case and this circuit board lest you damage it. Again, I used a wooden popsicle stick. Continue working evenly and gradually until the PDC is completely free of its housing. The fourth photo shows the bottom of the PDC and the printed circuit board which contains the three (3) internal relays and the PTC over current protection devices.

http://byfiles.storage.live.com/y1pp..._a7CPfqrinsZNQ

The fifth, sixth and seventh photos show the PDC's housing. The yellow toothpicks show the three (3) posts to which the plastic bosses were attached and into which I drilled holes.

http://byfiles.storage.live.com/y1pk...k8Ke4UTvd4bOrQ

http://byfiles.storage.live.com/y1pt...mDKDTAJU75Te9Q

http://byfiles.storage.live.com/y1pt...jIhSApEJ4KpcjA


13. Remove the printed circuit board from the PDC. This is accomplished by inserting a thin flat tool between the printed circuit board and the underlying plastic layer of the PDC. Do NOT use anything that might scratch the printed circuit board's clear protective coating or damage the etched circuits. A stiff plastic spatula or similar item works well. Work your way around the edge of the printed circuit board evenly and gradually, again so as to not bend or damage any of the terminal pins on the bottom side of the printed circuit board. Once you have a wide enough gap open between the printed circuit board and the underlying plastic layer of the PDC, you can switch to a thicker, sturdier item to continue to pry the circuit board free (I used popsicle sticks and tongue depressors). The eighth photo shows the PDC with the printed circuit board removed.

http://byfiles.storage.live.com/y1pp...HVQBp8VM2fJ5fg

14. Identify and locate the failed relay on the top of the printed circuit board. See photo ten. Turn the printed circuit board over (photo nine) and identify the four (4) leads (per relay) which must be unsoldered to remove it. Unsoldering the relay requires a suitable soldering iron (an 800-900 degree tip is suitable), braided copper wicking and a solder sucker (no jokes please - not absolutely essential but is helpful). It is also helpful to trim the relay's four leads as close to flush with the surface of the printed circuit board as possible before unsoldering them. Removal of the failed relay is not a "gorilla" task; the printed circuit board's copper circuitry is delicate and can actually be damaged (separated from the glass resin circuit board itself) by too much heat from an overly powerful soldering iron or attempting to remove the relay before all the solder has been removed from the leads. If you are not familiar with the use of solder wick and/or a solder sucker, I would suggest you seek out the assistance of an electronics geek to assist you. Once you have removed all the solder from the four (relay) leads it should be possible to pry the relay free of the circuit board, though it may be necessary to heat each lead with the soldering iron while you are prying if you were unable to remove ALL the solder. Once the failed relay is removed, clean any remaining solder from the four (4) holes in the printed circuit board with the braided solder wick and/or solder sucker. Clean any rosin or residue from the unsoldering process with aerosol contact cleaner so you will be able to make (new) secure solder connections.

http://byfiles.storage.live.com/y1pE...fK5-pZoqbdWTTA

http://byfiles.storage.live.com/y1p5...AC9reiBhCj4IQQ

15. Install new relay(s) and solder in place.

I used an American Zettler relay, part number AZ988-1AT-12DSEC3R.
I purchased the relay from RelayCenter.com, 17295 330th Street, Bagley MN 56621 Tel: (218) 694-6778 Fax: (218) 694-6780. The cost was $4.30 each in a quantity of six (6) plus sales tax and shipping.

Insert the relay's four leads into the corresponding holes in the printed circuit board. Make certain it is firmly and completely seated. Turn the printed circuit board over and solder the four leads in place. Photos eleven and twelve show the printed circuit board with the new relay in place.

http://byfiles.storage.live.com/y1pY...n6b7JGkCB6Gj4A

http://byfiles.storage.live.com/y1pU...XL4IC8-ByJ70ng


The repair is now complete and you are ready to reassemble the IPM/PDC. The reassembly process is the reverse of the disassembly process.

The most CRITICAL steps in the reassembly process are;
A. Remounting the printed circuit board on the base of the PDC. Make certain that all of the electrical contacts which go through the printed circuit board do so without bending them or folding them under the printed circuit board. I suggest counting the leads before and after, making a sketch or taking a photo for reference. Make certain the printed circuit board is firmly seated onto the base of the PDC.

B. Remounting the PDC into its housing. This can be a challenging task if you do not exercise patience and caution! There are 107 terminal leads which must be guided through the corresponding holes in the PDC's housing. These terminal leads are located in the seven (7) electrical connector recesses on the bottom of the PDC housing. I made a sketch of the bottom of the PDC housing, noting how many leads were in each column of each connector recess. This way I could be sure all the leads came through the housing and none were bent over and sandwiched between the bottom of the PDC and its housing. I STRONGLY SUGGEST you do the same. It is easiest to start the reassembly at the end of the PDC housing where the FCM was previously mounted. Proceed very slowly, cautiously and evenly until you see all the leads just protruding through the proper holes in the PDC housing. Confirm ALL the leads are present before you begin to gently seat the PDC into its housing. Slowly work your way around the edges of the PDC trying to keep the PDC even while you push down on it and seat the connections. Make sure the FCM connector slides into the two (2) channels on each side of the PDC's housing. Once the PDC is seated all the way, work your way around the edges of the housing where you previously marked the location of the seven (7) tabs/recesses ( Step 11) on the PDC and press firmly on the PDC at each location until you hear the tab "snap" into the housing recess.

Also make sure the tab of the B+ bus bar snaps into place in its housing (unlatched in Step 11).

Install the B+ terminal post and make certain it snaps into place (removed in Step 10).

Finally, check to make certain none of the fuses and relays have fallen out or become unseated.

Reattach the Front Control Module to its connector on the PDC and secure it with the four (4) screws from Step 7.

16. The final step of repairing the PDC is to secure the PDC to its housing at each of the three (3) locations where the plastic bosses were ground away. Originally, I was going to resecure the PDC to its housing using a small amount of structural epoxy. However, after hearing of so many repeat failures of the PDC, I decided to employ stainless steel sheet metal screws in the event I need to repair the PDC at some point in the future. I used #8 x 1/2" pan head ss sheet metal screws, but the size required is dependent upon the diameter of the holes drilled in the support post (Step 9), if any were drilled at all. As an added precaution against loosening due to vibration, I secured each screw head to the side of the PDC recess with a dab of silicone sealant which is easily removed if need be in the future.

17. Reinstall the IPM into the truck. Verify the problem has been corrected and HAPPY TRUCKING/TRAILERING!

Questions and/or comments regarding this article? Contact me via this board.

davidj54

This is an absolutely excellent post! Thanks greatly for taking us step by step through it.

The only thing I would have done differently would have been replace all three relays. Especially after seeing the photo of the failure mode of the relay you removed.

I noticed you bought 6 so you may have replaced all three.

ajpulley

Can you post the link to Part 1?

robbynne

Part 1 is a separate thread in this forum.

frmll300

Having trouble with lights not working on my 2003 . Came across this indepth post while searching info and thought i"d bring it up and include a link to part 1. https://www.dieseltruckresource.com/...1-t222371.html

walker1

What a great writeup! Lost my marker lights, and going to give this a try before I order a new box.

Thank you!!

FRONTI3R

Can you guys see the photos posted? I can't seem to see them. Have any ideas on what I need to do to see the photos you linked to?

Hawglip

I cant see them either.

Lary Ellis (Top)

The guy that wrote this article posted the photos some where other than this forum and they apparently no longer exist.