Trailer Brake problem, constant voltage on Brake wire

[FORDF250HDXLT]

i was just wiring up my dump trailer.it didn't have brakes at all which is against the law here in Maine for over 3k lbs.(i didn't run it without brakes! just bought it a few months ago) but plenty of trailers running around for sale without them i noticed while shopping....scary lol!
anyway,i went http://www.etrailer.com/faq-wiring.aspx as well before beginning.
all the wiring was old,so i was replacing all of it.i started with the lights,and i didn't get too far when i noticed the diagram there:
http://www.etrailer.com/Merchant2/graphics/00000001/pics/f/a/faq043_ss_500.jpg
didn't match what i had going on at all.i had just installed (100% correctly i know) a new updated 7 pin/4 pin .....well here it is:
http://www.amazon.com/gp/product/B001NYYREC/ref=oh_details_o01_s01_i00
http://www.amazon.com/gp/product/B005Q87T6E/ref=oh_details_o01_s02_i00
so i could do away with adapters and just have the newer style like modern trucks.there is a diagram right on the cover that contradicts what e-trailer has listed.
thinking i might have bought an oddball 7 pin updated plug for my truck,i then inspected my fathers 08 SD.and sure enough,our diagrams matched.
so i went by that instead of what e-trailer has going on.
it got dark on me by the time i had everything wire loomed and tied up nicely,but did take her out a bit anyway.nice lights,blinkers,even have a nice set of backup lights too boot.
iv got one wheel locking up for some reason,so i'll have to check it out tomorrow.
this is the controller i went with:
http://www.amazon.com/gp/product/B0033WDGH6/ref=oh_details_o01_s03_i00
http://www.amazon.com/gp/product/B001GN6RPM/ref=oh_details_o06_s00_i00

i forgot about that dial on the side.maybe i just need to dial that in and it cures what ails 'er.

i wouldn't think you should have 4vlts coming out of your trucks connector on the brake line when nothing is pushed.im gunna have to check mine again.pretty sure there was nothing without the brakes on,but i could be mistaken.

if something is wired incorrectly,you just need to trace them out,and simply pull the trailers 7 pin connector apart (pretty simple) and swap your wires right in there.
but you want to start with the truck.make sure everything is 100% correct before you worry about the trailer.

 

[Fozz]

Have you towed with this truck before with no problems?....if so, and you've had two different brake controllers in the truck and they're doing the same thing, the truck isn't the problem. Start looking at the trailer side of things. Check the easy stuff first, if you have a brake/tail light out on the trailer the filament can weld itself (if you will) to the ground part of the bulb. This happened to me once. Essentially, the brake circuit is partially grounded thereby partially brakes applied when the plug is plugged in. Then check the integrity of the trailer plug. Most electrical problems (my experience) are grounding issues, either no ground (broken wire or bad connection) or a poor ground (partially grounded, but not a good solid electrical connection to ground). Good luck

 

[cardana24]

When the brake pedal isn't being pushed do you have any voltage coming from the brake light switch to the controller?

I will check again. But last time I checked I did not have voltage coming to the controller when the brakes were not being applied.

Go to etrailer.com and dig around the instructions and get the wiring diagrams and look VERY CAREFULLY at the plug pinouts for the 7 pin connector and make completely sure that someone has not wired the connector backwards that goes to the brake s. SOmeone before me had done that on my truck and it gives you constant voltage going to your brakes because that becomes system ground and it is getting negative voltage constantly through the brakes and then when you hit the brakes it simply shorts voltage to ground on the trailer. I would get a roughly 4 .5v reading as well. I ended up rewiring everything.. The boneheads that installed the bed on that thing , if they had a brain, they would have taken it out and played with it. The truck has the tow kit and instead of using teh fuses and relays for the trailer or the brake controller plug in, they butchered teh harness and had ALL the lights running off the cab lights and brake controller hard wired in with gumby wiring running along teh frame. It all had to go.

I have already pulled my plug appart at the rear of the truck and it is wired correctly.

I dont know what type of controller you are using but some controllers have an inertia sensor in them to actualy apply the brakes and those units have a LEVEL SENSOR ADJUSTMENT SCREW on the side oppisite of the application adjustment control ... it usualy has to be turned with a nickel or dime the way the slot is designed .... otherwise if the brake controller just works on brake light input like my cheap one that applies the brakes to whatever I have them set to .. just bringing up the voltage slowly ... My type will test hot at the trailer plug all the time ... but when there is nothing hooked up I get an E1 code on my display and when I plug in the trailer it gives me the % reading that the brakes are set at ... if it is inirtia activated the LEVEL sensor setting is crutial and will apply the brakes all the time if not properly set ..or not come on at all if the oppisite direction ... but you should be getting either a red light or an error code when the trailer is unplugged ... if not your probably shorting into your taillights somehow or brakelights or turnsignal .. only a light will give the unit a false reading and make it think it has a trailer attached ... goodluck I hope this helps ...

I do have an inertia type controller. I will have to look up the model but it was ~$100 from advanced auto. It is mounted level but I have never looked for an adjustment screw. I also have manual syle controller that you use a dial to increase or decrease the voltage, and last time I hooked that one up I was getting the same 4 volts at the rear with out the brakes being pushed, so I don't think it's the controller.

Have you towed with this truck before with no problems?....if so, and you've had two different brake controllers in the truck and they're doing the same thing, the truck isn't the problem. Start looking at the trailer side of things. Check the easy stuff first, if you have a brake/tail light out on the trailer the filament can weld itself (if you will) to the ground part of the bulb. This happened to me once. Essentially, the brake circuit is partially grounded thereby partially brakes applied when the plug is plugged in. Then check the integrity of the trailer plug. Most electrical problems (my experience) are grounding issues, either no ground (broken wire or bad connection) or a poor ground (partially grounded, but not a good solid electrical connection to ground). Good luck

I have not towed much other than with this trailer, and the brakes have never worked properly since I have owned it. I have a feeling there is a problem in the trucks wiring.

*I also keep blowing the fuse for the left rear trailer brake/turn siginal.

 

[EMD_DRIVER]

Have you checked the voltage on BOTH sides of the break-away switch? One side should have at least 12.6v (With a fully charged battery.) and the other one dead. When I picked up my 97 travel trailer, I thought the pin in that switch had been broken off but still inside the housing. I found that the pin was completely missing, when I tried to pull the trailer the first time. When I hit the brakes, I was getting 10-12v showing on the controller. Not having a spare, I simply cut one of the wires to it. I was able to get the trailer home (8Miles) safely and have a completely new switch mounted now.

 

[cardana24]

Have you checked the voltage on BOTH sides of the break-away switch? One side should have at least 12.6v (With a fully charged battery.) and the other one dead. When I picked up my 97 travel trailer, I thought the pin in that switch had been broken off but still inside the housing. I found that the pin was completely missing, when I tried to pull the trailer the first time. When I hit the brakes, I was getting 10-12v showing on the controller. Not having a spare, I simply cut one of the wires to it. I was able to get the trailer home (8Miles) safely and have a completely new switch mounted now.

That was my initial thought when I was having this problem, so I bought a brand new breakaway switch, and I was still having this problem so I cut the wire going to the brakes to take it out of the equation.

 

[cardana24]

I just checked. The controller I have is made by Hopkins, it's the Agility model. It's an inertia controller. I just read the insallation instructions again and there is no mention of an adjustment screw.

I made an appointment with a local trailer place to have them look at it, and rewire what needs to be.

 

[EMD_DRIVER]

Where in Virginia are you?

 

[cardana24]

Where in Virginia are you?

I live in Madison County. About 20 miles north of Charlottesville. Central VA

 

[EMD_DRIVER]

I live in Madison County. About 20 miles north of Charlottesville. Central VA

Ok.. If you were closer to Winchester, I was going to offer some assistance.. I can't make it down that far any time soon...

 

[cardana24]

Ok.. If you were closer to Winchester, I was going to offer some assistance.. I can't make it down that far any time soon...

I appreciate it man. I am about an hour and 45 minutes from Winchester.

 

[laserjock]

Random thought. I ran into a crazy install once. Turns out the color code on the wires between the pig tail and the controller were different. I chased it for hours. Never occurred to me they might not be completely standardized at this point. It caused all sorts of weirdness. Might be worth a quick check against the little paper tags on the pigtail and controller or the books. I got my pigtail from etrailer I think. I believe that they did not match the standard brake control. It was a while ago so I don't remember which side was goofy. Of course the other answer is usually ground.
Good luck.

 

[racer30]

Left turn and Brakes are side by side in the 7 way plug. If you are blowing left turn fuse's you have a strand of wire or some blue corrosion touching between LT and BK on one of the 7 way sockets or plugs in the system. this will cause intermitant braking problems and harsh stops when putting on the brakes or turning left will pulse the brakes on the trailer. Just my 2 cents......over 25 years as a RV Master tech... seen it many times

 

[cardana24]

Random thought. I ran into a crazy install once. Turns out the color code on the wires between the pig tail and the controller were different. I chased it for hours. Never occurred to me they might not be completely standardized at this point. It caused all sorts of weirdness. Might be worth a quick check against the little paper tags on the pigtail and controller or the books. I got my pigtail from etrailer I think. I believe that they did not match the standard brake control. It was a while ago so I don't remember which side was goofy. Of course the other answer is usually ground.
Good luck.

I'll check that....I feel like it is probably something easy but I have looked at it so many times I am tired of looking at it and probably overlooking something simple.

Left turn and Brakes are side by side in the 7 way plug. If you are blowing left turn fuse's you have a strand of wire or some blue corrosion touching between LT and BK on one of the 7 way sockets or plugs in the system. this will cause intermitant braking problems and harsh stops when putting on the brakes or turning left will pulse the brakes on the trailer. Just my 2 cents......over 25 years as a RV Master tech... seen it many times

I have had the socket pulled apart at the rear of the truck and nothing is touching there (at least no obvious). Is there a common place to check? I noticed a bunch of nicked up wires to the left side of my rear fuel tank.

 

[FORDF250HDXLT]

well you can't have nicked up wires on your truck,so of course you should start with that repair first.
don't just repair the nicks either.see the issue is,that corrosion likely got inside and it has spread rapidly up each side of the wire.
you might want to consider just replacing the tow harness wires completely,depending on what you find by the tank.it might save you loads of hassles, not only now but down the road.

tip;
if you find lots of corrosion in your tow harness wires,and decide it's best to just cut 'em out and run new wires,consider running the new wires inside a section of old garden hose under there,to protect them for good.

 

[cardana24]

well you can't have nicked up wires on your truck,so of course you should start with that repair first.
don't just repair the nicks either.see the issue is,that corrosion likely got inside and it has spread rapidly up each side of the wire.
you might want to consider just replacing the tow harness wires completely,depending on what you find by the tank.it might save you loads of hassles, not only now but down the road.

tip;
if you find lots of corrosion in your tow harness wires,and decide it's best to just cut 'em out and run new wires,consider running the new wires inside a section of old garden hose under there,to protect them for good.

Yeah, I told the shop that I am dropping the truck off to that I think the truck needs to be rewired. My appointment is on Wednesday the 28th.