04 2500 trailer turn signal circut

[99guy]

Lost the LH turns on the trailer. Problem is in the truck. I see from the schematic there is a LH and RH trailer turn signal relay in the IPM. Anybody shed any light on this? Already done all the fuse checks, all OK. Truck had to leave the shop this afternoon, and I am just wondering when it comes back where to look next. Factory tow wiring, by the way. TIA

 

[99guy]

bump

 

[klenger]

Here's the drawings: http://www.klenger.net/dodge/7-pin-connector-installation/trailer-tow-wiring.pdf

 

[99guy]

I took a look at that schematic this afternoon, are the trailer turn relays shown going to be replaceable or are they part of a circut board?

 

[Bob4x4]

They are replacable,but more likely a fuse issue



Bob

 

[TowPro]

If it’s just the Left turn on the trailer I would check fuse 46 (15A). It supplies the power to run the relay and the 12V feed through the relay.



I would expect this relay to "click" on and off as the turn flashed.

Pull the relay, pin 30 should be 12V all the time, pin 85 should be 12v all the time, pin 86 is a Negative signal from the Front Control Module that turns the relay on and off, this pin applies ground to the relay to energize it, pin 87 is positive output from relay to trailer tow harness, 87a is not used. The relay is really a SPDT so when it’s "off" pin 87A is hot, but not used for any wires.

If relay is working correct, check continuity between pin 86 in IPM to LT wire in trailer harness, if it’s open you got a broken wire or connection somewhere.



Here are the electrical drawings Trailer wiring is starts at 8w54-1. Fuses are shown on 8w54-2.

 

[99guy]

Hey TowPro

I agree with your analysis completely, fuse 46 is good as is #47 for the right side. Perhaps I am missing something obvious ... but I have a sinking feeling that the relay is integral to the internals of the IPM. I have traced the L673 18 YL wire down out the botton connector of the IPM, no 12 pulse even though I hear the relay click, which confirms fuse 46 is good as well as the front control module. Checking the right side on fuse 47, I have a clicking relay AND 12 volt pulse on L674 18 LG as I should.



When you remove the cover of the IPM, (pic at 8W-10-3) the tow relays are not the relays you are loking at, best I can tell, besides, I pulled them all one at a time and the clicking neverstops.



Wondering then if the tow relays are part of the integrated circutry encased in the IPM box itself???? Again, perhaps I am missing something obvious. :{



Thanks

If it’s just the Left turn on the trailer I would check fuse 46 (15A). It supplies the power to run the relay and the 12V feed through the relay.



I would expect this relay to "click" on and off as the turn flashed.

Pull the relay, pin 30 should be 12V all the time, pin 85 should be 12v all the time, pin 86 is a Negative signal from the Front Control Module that turns the relay on and off, this pin applies ground to the relay to energize it, pin 87 is positive output from relay to trailer tow harness, 87a is not used. The relay is really a SPDT so when it’s "off" pin 87A is hot, but not used for any wires.

If relay is working correct, check continuity between pin 86 in IPM to LT wire in trailer harness, if it’s open you got a broken wire or connection somewhere.



Here are the electrical drawings Trailer wiring is starts at 8w54-1. Fuses are shown on 8w54-2.

 

[JDubien]

My dad has a 2003 and has the very same problem. Fuses are good too. He has not taken the time to get it fixed yet. I'm curious as to the solution. I just wanted to let you know your not the only one with this problem. Good luck!

 

[TowPro]

I used to work for the company that draws the diagrams for Dodge. I have a buddy that still works there so I emailed him the other day about a question for the 06. On the 06 drawings the relays are gone, so are fuses 46 and 46. he said the relays were taken off the drawing in 06 because they are not replacable, you have to replace the module. I assume that means in 05 and earlier they can be replaced?



I have seen relays get deposits on the contact (caused by a short) and appear as an "open" even though the relay still moves (clicks)

 

[TowPro]

Looking at 8w-10-3 I see a picture of the IPM.

It shows all the relays with names pointing to them.



Then on pages 8w-10-7 through 8w-10-10 they show each relay called out with pin numbers. I printed the picture of the IPM and checked off the relay as it was called out in the pages 7-10. Problem is the pages 7-10 showed relays for Horn, L turn trailer and R turn trailer, but they are named in the picture of the IPM. they must be there put in some positions named as "spare" as there are 8 "spare" relays on the IPM.

 

[99guy]

update

After laying the IPM out on the fender this morn and scratching my head I ran the schematics in to local dealer and talked to a good tech I know and the parts guy. They suggested pulling the relay but after I showed them the schematic, they looked some more and came to the same conclusion. Tow relays at least for factory tow option are integated in the IPM, No chango --- IPM $266.



Picked up a relay and couple of fuse pigtails and will wire the relay to the truck turn/brake back by the tow plug and run that way for awhile.



Dissapointed to see engineering chose to go this way, looks like a mistake to me. $266 is afordable but I am concerned as to what caused the problem, short in the trailer???? Two trailers, both newer units but I would hate to throw 266 bucks at it and blow the IPM again, or perhaps it was just poor quality to begin with, don't tow excessive with this truck.



Warranty expired for this problem so ...



Thanks for the replies ...

 

[99guy]

OK, I give up ...

Can't do it with a relay driven off the truck turn / stop either. Best I can tell is the front control module provides a low side driver for the turn / stops on the truck. Adding a relay may change the amp draw on the circut enough to ... ??? Anyway, I'm just guessing at this point. Looks like I am going to be ordering a IPM. Read the thread on the 06's, guess that looks worse.

 

[TowPro]

Did you open up the IPM? Maybe there is a relay inside it you can replace.

 

[99guy]

I plan on opening the old one up to see what can be done with it as soon as replacement arives. At best I might have a spare, and at worse I won't have lost anything. I'll repost my findings at that time. Have a good one!