Trailer Troubleshooting?

[tex25025]

Does anybody know if there are manuals, websites or something that I can look at to get a wiring diagram and discussion on how to trouble shoot trailer brakes(either 2 or 4 systems)? I'm checking for a short as my tow command system(the ford intergrated trailer braking system) won't work if it senses problems. I have checked using an ohm meter and the only time I don't get a read is on the brakes, I jump the brake wires at the trailer plug and test the line on the end that attaches to the brakes themselves and I get a signal, so it is something to do with the brakes and I don't know enough about troubleshooting them in order to determine what is wrong. Any thoughts, suggestions, ideas? Thanks.

 

[DirtHauler]

Have you checked the plug on the truck to see which wire is hot when the brakes are applied? You may have to rewire the trailer plug to match the truck plug as there is no set standards for vehicle/trailer wiring. I had to do this with one of mine.

 

[kenmac]

Make sure you have a good ground. If yours is like mine & used very little , the trailer sits out in the elements & things start to rust

 

[Bob_Skurka]

I had HUGE problems with a trailer that would work great with 2 of my tow vehicles but would not work at all with one of my vehicles (a Touareg). It had me baffled for almost a year. It turned out that the trailer, which was wired with all super efficient LED lights, did not have enough of an electrical draw to work properly with the truck wiring of one vehicle. But like I said, it worked perfectly with my other 2 tow vehicles. The fix ended up being very simple, but it took a year to figure out. The LED's simply didn't draw enough current and the truck's electronics were so sophisticated that it presumed the trailer was not wired properly. Ultimately the rear trailer light modules were replaced with inexpensive incandescent lights and everything has worked perfectly since.

If you are dealing with a new trailer and an existing truck, or a new truck and an existing trailer, its worth checking to see if the lighting types are compatible.

 

[Bird]

Several years ago, I bought a book from the Good Sam Club that was a general RV maintenance book and had an excellent chapter on electric brakes, but I don't know where to get that information now. The last time I worked on electric brakes that were not working was on my brother's fifth-wheel RV. The brake wiring was run through the axle tubes and he had driven enough on bad roads that it had moved around inside the axle until it wore the insulation off the wire and let it ground itself. To make matters worse, there was some water inside the axle tube with the bare wire.

 

[tex25025]

Have you checked the plug on the truck to see which wire is hot when the brakes are applied?

As a fail safe to protect the truck, if the tow command system sense a short or electrical problem in general it denies power to the trailer in order to protect the truck.

You may have to rewire the trailer plug to match the truck plug as there is no set standards for vehicle/trailer wiring. I had to do this with one of mine.

Strange thing is that I have had the truck and trailer the same length of time(little over a year) and it had worked up until now.

Make sure you have a good ground. If yours is like mine & used very little , the trailer sits out in the elements & things start to rust

It had tested good when I jumped the brake wires at the plug and ran the ohm meter on the brake end.

The brake wiring was run through the axle tubes and he had driven enough on bad roads that it had moved around inside the axle until it wore the insulation off the wire and let it ground itself. To make matters worse, there was some water inside the axle tube with the bare wire

My wires are exposed and they run along side the rear axle and to me they all look good. I believe it is something directly related to the brakes.

I had HUGE problems with a trailer that would work great with 2 of my tow vehicles but would not work at all with one of my vehicles (a Touareg). It had me baffled for almost a year. It turned out that the trailer, which was wired with all super efficient LED lights, did not have enough of an electrical draw to work properly with the truck wiring of one vehicle. But like I said, it worked perfectly with my other 2 tow vehicles. The fix ended up being very simple, but it took a year to figure out. The LED's simply didn't draw enough current and the truck's electronics were so sophisticated that it presumed the trailer was not wired properly. Ultimately the rear trailer light modules were replaced with inexpensive incandescent lights and everything has worked perfectly since.

If you are dealing with a new trailer and an existing truck, or a new truck and an existing trailer, its worth checking to see if the lighting types are compatible.

This particular flatbed and truck are the same age and both have worked fine up until just last week when I was hauling my 1435 to the shop.

 

[Farmwithjunk]

Try this site for some very basic info

http://www.farmco.com/technical%bulletins.htm

Keep in mind about 75% of trailer electrical issues involve bad ground.

 

[wushaw]

All your brakes are tied together, if one has a shorted magnet or shorted wire then your controller won't work. Check for the obvious easy stuff then start removing wheels and hubs.

 

[tex25025]

Try this site for some very basic info

http://www.farmco.com/technical%bulletins.htm

Keep in mind about 75% of trailer electrical issues involve bad ground.

Link wouldn't work, said the page was no longer valid. Also I had put the ohm meter on there to check for continuity, if it was a bad ground wouldn't one symptom of that be that nothing would register has having a stable connection, since your putting one connection on the ground wire and the other one at the various other connectors(right turn, left turn, brakes, running lights etc.)? How would you check for a shorted magnet? I'm pretty sure if it was a shorted wire I wouldn't read continuity when I bridged the ground and the brake wire at the plug and unhooked it from the brakes and tested it then with the ohm meter and I do get a signal when I test the wire with the brakes disconnected, but when I run the test with the brakes going thru the wire is when I don't read continuity.

 

[kenmac]

Can you (or) have you jacked the trailer up & run a hot wire straight from the batt. & connect it to the hot wire going to the trailer brakes ? ( without going through the brake controller ) If the wheels lock down doing this , I would say it is the controller.

 

[tex25025]

Can you (or) have you jacked the trailer up & run a hot wire straight from the batt. & connect it to the hot wire going to the trailer brakes ? ( without going through the brake controller ) If the wheels lock down doing this , I would say it is the controller.

Thing is and this is what has got me if it is the controller particularly since it has worked up until now, is that I hooked up my truck to the horse trailer and the system worked then. The difference between the horse trailer wiring and the flatbed wiring is that the horse trailer doesn't having any wire on just the accessory position and on the flatbed I just have right and left turn, brakes, and ground everything else is open.

 

[KICK]

its fairly common for Green to be right turn-brake

Yellow to be left turn/brake

brown to be running/tail lites

rest of wires are ground and brakes and possibly accesory

 

[Egon]

Trailer wiring does have a set standard. A site.

Trailer Wiring Diagram For 4 way, 6 way and 7 way circuits

Have you checked the connections at the back of the truck where the plug connections are spliced in to the truck wiring? They may corrode over time.

A meter may help for checking things out.

 

[George2615]

The last poster (Egon) has the link you need to see. The blue wire is for the brakes as shown. Using a 12V jumper wire touch it to the trailer plug blue wire while someone checks each wheel on the trailer to see if the magnet is energizing. If not you may have a break in the wiring or a bad magnet in the hub.

The most common problems are corrosion in the wiring plug terminals, corroded wire inside the truck or trailer plug, bad or missing ground, broken wire under trailer possibly ripped off by a road hazard. I rarely get more than a year on mine before I have to rewire the plug. Winter road salt around here just gets inside the plugs and works its magic.

 

[Farmwithjunk]

Link wouldn't work, said the page was no longer valid.

Try this one. Same site but a link that should work.

Farmco Distributing Inc

Or search "Dexter Axle" . Dexter makes the lions share of trailer brakes.

 

[KICK]

after you wire a new one, I usually seal the end with RTV.

also some grease in the plug.

doesn't stop corrosion but it does slow it down.

 

[George2615]

I do use grease on mine. Have tried silicone sealant but the salt always finds a way inside. My 2006 tilt bed trailer with need a repaint this year already. It looks about ten years old right now. I don't mind the snow, just hate the overuse of road salt.

 

[Stimw]

How I check each wheel brake is I hook up a battery charger to the plug and run an extention cord to the rear. Jack up each wheel and plug in cord to power the brakes and spin test.
All trailer plugs and recepticals have a specific pin position and wire has a color code. Some people don't follow the codes.