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ttbikes · 05-21-2014, 07:34 AM

I had new axels, brakes and 7 pin connector replaced on the 64 Tradewind I am bringing back to life. But I have run into a problem. I am having trouble getting the cause of the problem figured out. The first time happened at about 4000 miles into a 6000 mile trip. The brakes worked for the first 4000 miles. I stopped for the night and the next morning when I would touch the brakes they would lock but then disengage when I would take my foot off the brake. Changing the gain on the controller had no effect on the grabbing. I nursed it along 5 miles to the nearest trailer doctor. They put a meter on it and at first they were not sure it was getting enough voltage to the controller but then decided it was. The only variable that changed in the process was taking the 7 pin in and out a few times. They said the brakes should be working and they were. My best guess was that maybe dust got in the 7 pin (although I am not sure I even disconnected it that night) No trouble for the last 2000 miles. Next trip was a short 20 mile camp outing with no problems. The trip after that was a 1000 mile round trip with no problem on the trip down but when we broke camp the grabbing was back. After about 20 miles of playing with the 7 pin the brakes worked fine all the way back home. I took it straight to my trailer guy who did the original work but of course we could not find any thing wrong because the brakes were working. They worked for the next 20 mile trip and then I put the trailer up for the winter. I just got it out yesterday to start some projects at my house and as I pulled out of my slot and touched the brakes they grabbed, so I drove slowly around the near by State Park with no problems. I had also moved around the storage lot a couple of times without trouble during the winter. Leaving the state park, I got a short grab (tires squeaked) but then they were fine for the six mile trip home. Every time this has happened the trailer was parked in dusty conditions so there is a correlation there but I have no idea the cause. Playing with the pin shows correlation but still no idea on cause. The interval the trailer was parked ranged from one night to four months. I am going to talk to my trailer guy again but wanted to get some opinions before I do. Thanks in advance.

87MH · 05-21-2014, 08:09 AM

My first thought for probable cause 1s:

The brakes on the trailer are incorrectly wired to the brake lights. The process of getting the older AS umbilical wires tied into the proper pin position of modern tow vehicle 7 pin hookups is well documented. When I picked up the '78 Sovereign in Ohio I spent a rainy and cold afternoon in a Walmart parking lot attempting to sort out the wiring issues. The wiring difficulties did not help my attitude during the tow from Ohio to Texas - took one day longer than planned.

Can you check for both voltage and amperage in the umbilical brake line circuit while someone applies the brakes in the tow vehicle?

Skater · 05-21-2014, 08:21 AM

Another theory - something is shorting to your brake wire. For example, if the +12 volt constant wire was occasionally hitting your brake's wire, the brakes would come on at full power. First place to look would be in the 7 pin connector...beyond that it'd be tracing wires.

**Action** · 05-21-2014, 04:12 PM

I have seen drums that get rustly and shoes (or may be this case is a magnet) get hung up on the drum because of the rust.

Just a shot in the dark, however I have seen this on the rear drum brakes of some cars that sat for a long time. The rust took some time to wear off after the brakes were used and it was inconsistant in at least one application.

Again just a guess and may be not the cause.

>>>>>>>>>>>>>Action

HowieE · 05-21-2014, 04:48 PM

Brakes will grab after sitting for a prolonged period of time. This generally is on the first few application and do to rust on the drum face. Not your problem.

Does your brake controller have an amp read out and if so what amperage is displayed when the brakes grab? If the amperage is high at that point the problem is in the controller. If the amperage is normal for the pressure you just used to apply the brakes than the problem is rearward.

The spacing between terminals in both the receptacle and plug is minimal so I would open both checking for a possible short between wires. I like to soldier in place and then tape between each connector to ensure against problems like this.

If the controller, receptacle and plug check out OK has anyone checked the adjustment of the brakes. I have seen brakes using a single return spring on the shoes hang up and not release both shoes from time to time.

ttbikes · 05-22-2014, 06:41 AM

I am getting some good feed back here. Thanks.

I do not think it is rust or dust on the brake drums. I have experienced that on vehicles and this is more pronounced. This is more like the brakes have been completely engaged. When I take my foot off they release normally. The intermittent part I would think implies a short or something loose.

There is no voltage reading on the controller unfortunately. Do controllers go intermittently bad or do they just fail? Looks like maybe my best bet is to dig into the 7 pin or have the guy who wired it take a look. I am assuming the female part of the connection would be less likely because it is a new vehicle. Anyone have additional thoughts? Electronics are not my strongest area.

xrvr · 05-22-2014, 06:48 AM

Have seen brakes that grab the first time or two used whenstarting out. I just thought it was dampness, always worked okay after the first few tries. Does your problem persist or is it only once or twice.? I do not think this is your problem but, who knows? Jim

HowieE · 05-22-2014, 07:57 AM

If the brakes ARE GRABBING while you have your foot on the brakes and RELEASING when you let up I think we can assume the problem is not in the wiring of the plugs or in the wiring of the trailer. I would look closely at the controller since that is about the only source of current of that magnitude and controllable by the brake pedal.

A short in the plugs or trailer wiring would not be effected by the brake pedal.

If you can get another controller for a trial I would wire it in and try that.

perryg114 · 05-22-2014, 08:11 AM

Worn magnets can cause problems as well as brakes being adjusted too tight. I had to back off on the adjustment on a couple of my wheels. Also if you have any grease on the drums they will grab. Standard brake controllers are on-off with a bit of delay before full application. The speed you are going also affects how much braking you get. Trailer brakes seem to work much better at slow speeds than at high speeds. It maybe you need to back off the adjusters on the offending wheels or back off the voltage on the controller. If you back all the way off the controller voltage and the brakes are still locking then they are wired to the brake lights or something. Worn magnets can make the locking problem worse.

Perry

ttbikes · 05-22-2014, 10:41 AM

Quote:

Originally Posted by HowieE

If the brakes ARE GRABBING while you have your foot on the brakes and RELEASING when you let up I think we can assume the problem is not in the wiring of the plugs or in the wiring of the trailer. I would look closely at the controller since that is about the only source of current of that magnitude and controllable by the brake pedal.

A short in the plugs or trailer wiring would not be effected by the brake pedal.

If you can get another controller for a trial I would wire it in and try that.

The breaks only grab when my foot is on the brake. When I take my foot off the break there is no drag. Also I should have said it is like I have slammed on the brakes. The thing that had me steering away from the controller was that it did not happen every time. Also while it is happening adjusting the gain had no effect. I guess I will try to borrow a controller and see what happens. If I need to buy a new one, any recommendations?

Pileus · 05-22-2014, 11:01 AM

Some brake controllers are sensitive to tilt. The more the controller is tilted from level, the more "grab." Did the controller get knocked into a steeper mounting tilt when your problem began?

Skater · 05-22-2014, 11:46 AM

Quote:

Originally Posted by ttbikes

The breaks only grab when my foot is on the brake. When I take my foot off the break there is no drag. Also I should have said it is like I have slammed on the brakes.

Yeah, then I'm leaning toward some issue with the controller as well. I used a Tekonsha Prodigy when I had the B190 with the tow dolly and I really liked it.

perryg114 · 05-22-2014, 12:06 PM

Measure the voltage at the plug and see if it changes based on the gain setting. Just blindly replacing stuff is not the answer. You might go through half a dozen controllers before you find out it is not wired correctly. Also check voltages using the manual lever and by pressing the brake.

Perry

r carl · 05-22-2014, 12:26 PM

Seems like your brake light wire is powering your brake magnets. Full on or off.

HowieE · 05-22-2014, 12:36 PM

Let's look at this. If it were the brake lights and you are drawing 12 amps, 4 magnets at full power, plus the brake lights you would blow the brake light fuse.

Intermittent electrical problems are the hardest to figure out but logic can be applied and many things eliminated. Look to the things that can carry that amount of current and not fail themselves.

ttbikes · 05-22-2014, 06:40 PM

I am really not much of a meter guy but I most likely can check the voltage next time it happens.

It is possible that I nocked the controller to a less level position but it has a lever on the side and it is straight up and down as per instructions.

When the grabbing is not happening every thing works perfectly. The problem has been there about for about 1 1/2 hours total in 8000 miles of towing. While it has always happened at the start of a towing period the interval between the end and start of a towing period have been a matter of hours to up to 3 months. My approach has always been to play with the 7 pin and the controller until it goes away but I have never identified anything I did that made it stop which it always has sooner or later.

I think Howie might be on the right track but I would of thought a controller would either work or not work.

HowieE · 05-22-2014, 06:50 PM

Voltage. The controller output is measured in amps.

What you can measure is the voltage input to the controller. The battery voltage right after starting is low. It takes about 20 miles on the road to bring a battery to full charge.

On my diesel the glow plugs remain on for over minute after starting and the battery voltage is well below 11 volts. If there is a component in the controller that is susceptible to low voltage that may be it.

Condoluminum · 05-22-2014, 07:07 PM

The little trim adjusting lever on the side of the controller has a lot to do with grabbiness if it is occurring when you apply the brakes.. If it is pointing towards front of vehicle from perfectly vertical, it will lead to brakes grabbing.. If it is pointing instead towards rear of vehicle, it will feel like brakes are slow to take effect.. I'd try test drive and move lever towards rear and see if that cures grabbing brakes.. You can then adjust back towards forward until they feel correct.. No meter needed!

ttbikes · 06-11-2014, 07:43 AM

So I believe I may have fixed the problem and if I am correct it makes me feel a little dumb. My controller (Hayes Energizer III) has a operating range for level (-35 degrees to 90). The controller was knocked off level close to the limit but not over it. I had checked the lever on the side for the correct position and every thing operated normally under normal conditions. However, on steep downhill grades the controller was outside the level operating range just enough to cause the brakes to grab. By far the biggest problem I had was in the Ozarks, but because it was so infrequent, it had me assuming a short. In addition, the first time it happened was starting out on a flat road. I now believe I fixed it the first time by adjusting the lever which made it operational under most conditions. I took the trailer back to the Ozarks this week-end and had no problems. I still may be whistling in the dark, but I hope not. Does this sound possible to you all?

r carl · 06-11-2014, 09:58 AM

Quote:

Originally Posted by ttbikes

So I believe I may have fixed the problem and if I am correct it makes me feel a little dumb. My controller (Hayes Energizer III) has a operating range for level (-35 degrees to 90). The controller was knocked off level close to the limit but not over it. I had checked the lever on the side for the correct position and every thing operated normally under normal conditions. However, on steep downhill grades the controller was outside the level operating range just enough to cause the brakes to grab. By far the biggest problem I had was in the Ozarks, but because it was so infrequent, it had me assuming a short. In addition, the first time it happened was starting out on a flat road. I now believe I fixed it the first time by adjusting the lever which made it operational under most conditions. I took the trailer back to the Ozarks this week-end and had no problems. I still may be whistling in the dark, but I hope not. Does this sound possible to you all?

Yes, something was powering your brakes once in awhile.