Trailer Wiring Problem (HELP!)

[bigflatdaddy]

I'm leaving for a trip tomorrow and have a problem with the left turn signal and brake light on my trailer. After sigificant diagnostics, I know that the fuses are good, there is power at the fuse rail, but there is no power at the trailer plug for the left turn signal. As the truck has the upper and lower plugs for trailer lights, I tried both and they are both dead. All truck lights work fine - no issues at all.



Any thoughts would be great... . arrrrgh... .

 

[jelag]

there is a separate fuse in the truck for the trailer circuits... either look at the printed information on the underside of the lid... its something like ""left side lighting""... .

Or take a test light with a sharp probe and test each side of each fuse and find the bad one... .

I assume that you put the test light into the female part of the plug and tested the pin at the 9 o'clock position (left turn)

Hope this helps. .

 

[bigflatdaddy]

Thanks. Yes, all fuses under hood were good, including those dedicated to trailer. Are there fuses located somewhere else? In cab? Along wiring? Any help is appreciated. Rinning lights fine too, just no left turn or left brake.

 

[HHhuntitall]

It's common for me to see a lot of plugs corrode and lose contact(or just not properly installed) at the back of the plug. The wire either loses contact, falls out, or is loose and working intermittently. I'd suggest going under the truck and probing the wires under the truck, or taking the plug out and checking at the back of it. I presume the one in the bed was added aftermarket. If they just tapped the wire on the factory loom, and used a cheap tapping device, they can cut the wire, and neither one will work past that point... ... There is a possibility that the connector behind the driver side front tire could have a bad contact... . it was very frequent in the 2nd gens, I'm not sure I've seen that problem in the 3rd gens, but if it's there, you won't have any power from there back...

 

[DHD]

Also, check the bulb. The second element could be bad and the running lights still work. Sounds simple but has happened to me before.

 

[JMarketos]

Hope this doesn't waste your time, but reading jelag's response reminded me of an issue I had many years ago, and I want to mention it. I used a test light with the sharp "poker" probe to trace tail light wires on a car I had several years ago. (I think I was working on 4-wire trailer lights at the time). Then a couple years later, I discovered the left side tail lights on the car didn't work. Troubleshooting, I eventually discovered that salt spray from the Central New York winters had apparently gotten into the little pin hole I made in the wire with my test probe, and over the course of a couple years, had corroded the wire for at least an inch or two in either direction from the pin hole. I ended up replacing sections of the wire I had previously probed- the copper inside had turned to green powder. If you live in a salt climate, you may want to tape up the little poker holes in the wire insulation. I wish you best of luck tracing whatever is the main issue with your truck- hope it's something simple.

 

[Schumacher]

x2 with HHhuntitall, My cousin had the same problem with his '05. He lost 12v power lead and brakes.

 

[Big Hamp]

I had this same problem wit my '03 a couple of years back. On mine, doing exactly the same thing, it was my power distribution box. On the '03's sometimes instead of blowing a fuse, it will mess up the circuit in the power box before it reaches the fuse when there is a short in a trailer. The local dealer replaced my power box and it was fixed and has been fine since. Maybe this is not your problem, but I wanted to let you know.

 

[ScottRoberts]

I had a similar issue for years, thought it was the trailer, not the truck. Turns out it was exactly what Big Hamp said. Mechanic replaced it and all is well.

 

[Shadrach]

My 03 does the same thing. The dealer told it was a common problem and I should replace the silver box that's mounted on the outside of the under hood fuse panel. You have to remove the fuse box to get at it. I obtained a good used box from a wrecked 03 and will replace it when I get a chance. Shadrach

 

[TCDiesel]

Here's your problem. NEW TIPM is your only solution & replace 47/46 with 10amp.

 

[GCroyle]

TWest,



TIPM in english = ? What model years seem to have this problem?



What is the detail that you are trying to point out? pic is a bit fuzzy.



Thanks,



Gary

 

[Road Dog]

TIPM = Total Integrated Power Module It has inputs -- switches on your dash -- and outputs -- the lamps on your truck -- and controls them all. It also detects LAMP OUT, dims the interior in a pleasing manner and is expensive to replace.

 

[Prairie Dog]

Sorry gents, no TIPM on our 03's. Only 06 and on

Could be the FCM but thats not very common, I'm still thinking its a fuse .

 

[TCDiesel]

Ok... I will re-name to PDC (Power Distribution Center)... The FCM (Front control Module) has to connection to the circuits that run the trailer lighting.



The following functions are Controlled by

the Front Control Module: (2003)

² Headlamp Power with Voltage Regulation

² Windshield Wiper “ON/OFF” Relay Actuation

² Windshield Wiper “HI/LO” Relay Actuation

² Windshield Washer Pump Motor

² Fog Lamp Relay Actuation

² Park Lamp Relay Actuation

² Horn Relay Actuation

The following inputs are Received/Monitored by

the Front Control Module:

² B+ Connection Detection

² Power Ground

² Ambient Temperature Sensing

² Ignition Switch Run

² Washer Fluid Level Switch

² Windshield Wiper Park Switch

² PCI Bus Circuit

 

[Prairie Dog]

I only wanted to point out what the differnce is, that the 03 does not have any electronic device to provide circuit protection like the TIPM does on later models. It (thankfully) relies on good old fashioned fuses. The FCM or PDC are rarely if ever damaged by short circuits from the lighting circuits whereas the TIPM must be replaced if "tripped" more than three times and can only be reset by someone with a STAR scan tool. These are two very different devices.

 

[Motorhead]

Here's your problem. NEW TIPM is your only solution & replace 47/46 with 10amp.

Is that FUSE 47/46 in the '06-'07's?

 

[TCDiesel]

03-05 46/47.

 

[GBergen]

trailer light relay on PDC?

I've been doing some looking around for an answer to the reason I have the right brake light on continuously, only on the trailer. I've come across several posts that refer to the PDC (Power Distribution Center) and issues related to the turn/stop relays that are on the circuit board. I must admit that most of the posts I've seen, reference trailer brake / turn lamps that are "out" instead of "on" continuously, like mine.
I have no idea if the SDC is related to your specific issue, however, I did want to mention it as a possibility. The weather in Idaho is cooling off and I will have a month or so to investigate and possibly repair the SDC before I need to tow again. I had considered a trailer power relay module, like one of these from Valley, but the posts I've seen, they work for folks that have trailer brakes that are currently out, and not on all the time like mine, so I don't think it will solve my issue.
I really don't like to advise going to another diesel truck web site for information, however, this guy did a great job describing and documenting the replacement of the relays on the PDC to fix his brake light issue.
Power Distribution Center (PDC) - REPAIR - PART 1 - Dodge Diesel - Diesel Truck Resource Forums <br>
Power Distribution Center (PDC) - REPAIR - PART 2 - Dodge Diesel - Diesel Truck Resource Forums <br>
Hope this is helpful or at least gives you another place to investigate for your particular issue.

 

[Shadrach]

I changed the FCM on my 03 and the left signal and brake on the trailer plug still don't work. Are these only controlled by a fuse? Or could it be something else? I'm not going to be towing till the spring so it's not critical right now, besides it snowed today so I will have to wait till the weekend when I can get into my buddies warm shop again. Shadrach