drooperhaley

Hi Guys,

On my 2004 there is no output on the left turn/brake light pin in my trailer tow plug. All the others are fine (ie right turn/brake, tail lights, battery power, trailer brakes). I've checked at the connection plug behind the bumper and no power there either with the left turn signal on. The yellow wire that should have power does not. The truck turn signals/brake lights work fine, just no power to the trailer tow plug for the left turn/brake light. Fuse number 46 is OK. The service manual schematic shows the power going thru that fuse to a relay in the Integrated Power Module that is supposed to drive that pin in the plug. The inside cover of my box shows no such relay.

I'm leaving to pull my travel trailer cross country in a week so I'd like to get that left brake/turn signal working on the trailer. Before I really screw things up, can anybody suggest how I can find that relay? Any other suggestions would be most welcome.

Thanks,
Bruce

Foxborough

I am not sure about your 2004 but the 2006 has just a control module between 12v power and trailer lights. If I get a short, I understand it is abound $200 part. People have put in fuses between the trailer & truck. I take it you checked the truck fuses. I believe it is the module is under the hood in the left front fender. Don't forget to find what shorted in the first place, might have wiring problems on trailer too. Looks like it is C8 for mine. Sorry not too much help.

drooperhaley

Kevin,

Thanks. I looked at the schematic. It looks like the control module triggers the relay (that I cant find) and the power goes thru fuse 46 to the relay. I would think a short would either ruin that relay or blow the 15 amp fuse. The control module (called the Front Control Module) should not be affected the way I read the schematic. That control module drives lots of functions and everything else seems OK.

Still wish I could find that relay.

Bruce

Oilguy

Power Distribution Box...

I have gone through 2 of them.... There is no fixing it unfortunately >>> you have to replace it... It is the whole box that contains the fuses under the hood... $250 part at dodge but I would check at salvage yards first...

Do a search for this problem on the forum and you will see that it is fairly common..... I wish it had external relays but instead the geniuses thought it would be a terrific idea to integrate a lot of substandard parts into one expensive substandard part... Go Figure!

OG

Foxborough

I added the schematic & relay location for my 06. That is all I have for you.

drooperhaley

OG,

Thanks, that is what I was beginning to believe. I pulled the box enough that I could check the yellow wire that is supposed to feed the plug for left turn. No power in it, but there is in the green wire for the right turn. If I pull the fuses (46,47) neither relay will click. If I replace the fuses one at a time, I hear a relay click but its not a plug in one. Since the relay clicks, I assume the Front Control module that triggers it is OK so the problem is either the relay or the wire/trace going from the relay to the output connector.

Do you know if the power distribution box is the same for various engines/years? That is, how likely am I to find one in a junk yard?

For a work around, I plan to jump between the actual turn signal wire feeding the bulb and the tow plug - like I would have done with an old truck. That wont give me a left brake light, but will give me a turn signal.

Thanks for the diagrams Kevin.

Bruce

Oilguy

Nah... I just happened to find one for an 04 diesel like my truck and swapped it in...
Your work around will work... I did that for a while the first time it happened and the dealer part was backordered for 2 weeks but I would NEVER do that again... I pull everyday around town and it if very difficult and stressful to get around in heavy traffic in a college town .
I had mine rigged to have brakelights and I should have done it the way your thinking and done it with directionals.... Oh well...

drooperhaley

Oilguy,

Did you happen so save your old module? I'd love to have it to tear apart and see whether there is any way of fixing them (I know its meant to be sealed). I called the Dodge dealer in our small town (Flagstaff, AZ) and they said it is unique to the 2004 Cummins - fat chance of finding a used one - and they dont have it and it would take a week or more to get it.

One other thought. RV places have a device that's pretty cheap that is made for foreign cars that are made with separate turn signal and brake bulbs to combine the two signals and output one to the trailer plug. None in our town now, but I think that should fully replace the lost functionality at a small fraction of the cost of the Dodge factory mess.

Bruce

Oilguy

PM'ed you....
BTW.... they are full of it... This issue is not unique to the 04 model and neither is the box... It does have a part number that has superseded it which makes it fun to look up in the dealers system.... All of the parts guys where I am can't find their butt with out a part number so they are no help and usually make up something to blow you off if they don't know the real answer...
As for the trailer lighting device your talking about... I have never played with anything like that... so I will be no help there.

If you do find a workaround please post it.... there are many people that would love to know how to do that....

OG

gcssr

do you have a signal for the L/H truck and not for the trailer. if so do you have the 4wire plug under the bumper, if so does it have power to the left signal. also if you are still having problems, email me at; gspencer@satx.rr.com, i may have diagrams i will email to you.

drooperhaley

Hi Grant,

Yeah, I have LH truck signal/brake lights but not on trailer. There is no power to either the 4-pin plug or the 7-pin plug. Oilguy, is absolutely correct on the problem. I traced the wire clear back to the power distribution box and there is no power in the yellow wire where it exits the box. The fuses are fine and you can hear the "****" relays that are built into the box click with the blinkers. Either that internal relay is not actually making contact, or what I suspect is that past the relay there is a trace on an internal circuit board in the PDM that is broken or burned.

I did a work around, but need a new PDM. Once I get a second one, I'm going to cut the old one apart carefully to see if it can be fixed and glued back together. This is REALLY poor engineering!

Thanks for your reply.

Bruce

motopatzo

Hi guys....I was just reading the posts in this thread and it looks loke Dodge screwed up designing this thing. Would a quick fix like running new wiring from the manual brake controller to the trailer connector and new wiring from the taillights to the trailer connector work????? This way it would bypass that module mess that Dodge created. Oh Ya.... and I would add an inline fuse as well

drooperhaley

Yeah, in fact your can splice into the brake, turn and tail light wires that run the truck right back by the plug. But as others have suggested, to really do a fine job, probably should fuse and use relays so as not to overload the circuits that run the truck. The other problem, is that the Dodge has separate wire/lights for turn and brake while trailers use a single filiment. As I understand it tho, there are devices (made for foreign cars that often use separate turn and brake lights), to handle that.

kingofdodge7131

I guess im not seeing a problem, why not just get a relay, hook it up so its always connected, to like the 87(just picking common numbers) So power always goes through it so your tail/brake lights work. Then when you want blinkers, the truck blinker powers the relay and it goes to a dead end, So basically it "applies the brakes" then "cuts them out" giving you a blinker. so for aprox 60 cents you could have this working fine.