Electric Brake problem

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New member
Jun 23, 2005

Just bought a mint conditioned 1991 30 ft Dutchmen travel trailer.  While the rubber looks very good on it I think I will replace the tires as I am not comfortable running 15 year old tires no matter how good they look.  Anyway, the electric brakes will lock right up when I hit the truck brakes the first few time when starting out for the day no matter what I set the gain at on the controller.  After they lock up the first few times I hit the brakes it settles down and performs fine.  The previous/original owner said this trailer did that from day one.  Any ideas why this occurs?  Thanks.
I had a similar problem with a previous trailer.  Never did find the cause.  It did it from day one and continued for 10 years even being towed by different vehicles.  One complete change of magnets and one new set of shoes did nothing to aleviate the grabbing.  A few miles down the road and they worked as they were designed to.  I always considered it a dampness problem but it didn't matter if the trailer was pulled everyday or after setting for a month or two.  I finally would back off the controller for a few miles and all worked well.  Oh yes, I changed controllers too.  Same problem.  The present trailer has a brake noise problem that is driving me nuts but I either roll up my window or shut off my hearing aids so I cannot hear them squeal.  ::) Everyone else does though! ;D
As others have told you, it is not an unusual problem but nobody seems to know why it happens.  It is often attributed to dampness (overnight condensation), but I don't think anyone knows for sure.

I had one trailer than was prone to this sort of thing and I got in the habit of touching the brakes as I pulled away from the campsite or my driveway.  That way I got the lock-up out of the way at ultra-low speed and where I was expecting it.  Also, try to avoid having it happen while on pavement - it's really tough on the tires!
Change the tires as soon as possable every manufacture will tell you that seven years is the max on tires. they will come apart and tear up your trailer.
While the rubber looks very good on it I think I will replace the tires as I am not comfortable running 15 year old tires no matter how good they look.

Damn fine idea.  Trailer tires should be retired after 5 years and certainly after 7.  I am surprised they still hold the trailer up. :)

Anyway, the electric brakes will lock right up when I hit the truck brakes the first few time when starting out for the day no matter what I set the gain at on the controller.  After they lock up the first few times I hit the brakes it settles down and performs fine.  The previous/original owner said this trailer did that from day one.  Any ideas why this occurs?

Does your controller permit setting the sensitivity?  Try fussing with that -- on a no traffic road.  Read the brake manual on how to do that.
One of the things that can cause the kind of symptoms you cite is rust.

When the trailer is sitting, a thin coat of rust happens on the inside of the brake drum

When the magnets engage, the first time or two, it's a rough surface and thus the magnets "Drag" kind of strong... Once the brake drum has made a couple of revolutions with the brakes partially engaged the rust is rubbed off and the brakes work normally

What can be done about it?  Well,  when you first pull out lightly, I mean LIGHTLY apply the brakes for the first 10 to 20 feet

Note, eveuntally this will wear out the inside "Face" of the brake drum.. Likely about 10 years after they wear out in the normal way (in short, don't worry about it)
Moisture seems to cause this problem. I notice it in damp weather more than in cold or dry times of the year, so rust may be a contrubuting factor.
Another question answered! We have just purchased our first RV (Montana 3400) and have what appears to be the same "grabby" brakes when we first start out. I have been very gingerly applying the brakes before we hit the highway and it seems to clear the problem. Also make sure to be very light on the brakes the first time or two I apply them.

Another newbie question I have related to electric brakes. We have the Prodigy controller and the manual says that for an RV that weighs 40% more than the tow vehicle(which ours does), the boost should be set at b3 and the power (is this what people refer to as "gain"?) around 6.0.  When we picked up the new RV from the dealer (who installed and adjusted all the systems including the brake system on our truck - a new Dodge Ram 3500 diesel - the boost was set at b1 and the power at 10.0. The brakes seem to work fine at these settings but I am a bit concerned/puzzled by the discrepancy between what the manual says about brake settings and how the dealer actually did it. I asked the tech manager about the matter and his reply was that the fellow who sets these things up really knows his stuff and is usually right on the mark with electric brake settings.

Can anyone provide enlightenment on whether to accept the discrepancy and the brakes that seem to be working well (remember, I have no previous basis for comparison) ... or change to the 6.0/b3 combination and adjust from there?


There are likely several combinations of "B" and Power settings that will work for any given trailer.  It well may be that the setting the set up man used is as good as, or better, than the factory recommendation.

And, though I've found that every dealer will always tell you how great their tecnichians are (NOTE: not just RV dealers) and it's a fact, some of them are great.

It's also a fact not all of them are.... I can tell you about the technician who put the new engine in my towed..... however I don't like melting monitors with the kind of language which is highly discouraged on this board.

I have the same controller and trailer about the same size. I never run at boost level one the trailer is not providing it's share of the work, I vary between 2 or 3 depending on the conditions. You must feel that the trailer is doing it's share equally without over doing it and pulling the truck back. I think the high gain setting is so that if necessary the trailer brakes will lock up if necessary.

Boost and Power (Gain) are complementary and there are many combinations of settings that will work adequately with a given tow vehicle and trailer.  There is no single right answer.

Power is an overall setting that defines how much braking is applied on the trailer. Boost is an initial braking parameter and according to Tekonsha is intended to provide some initial "extra" braking on heavy trailers.  Boost is helpful because the Prodigy is an accelerometer-based proportional controller, which means it senses how fast the tow vehicle is stopping and applies trailer braking accordingly.  There is a tiny time lag between application of the tow vehicle brakes and Prodigy's reaction to the deceleration it senses, so Boost can be used to momentarily force some extra braking at the initial application of braking.  Boost applies for about 2 seconds and then the normal Power setting applies.

For more information on how Bost works and choosing a setting, see Tekonsha's Boost Technical Bulletin. It is easy to understand, but you have to use a certain amount of trial and error to find what works best for your rig.


Nelson's settings sound to me  like a good starting place.
Thank you all for your responses. My sense was that the gain and boost settings were not correct even though they seem to work ok. I need to find an abandon airport runway or deserted road to experiment. Based on Nelson's experience, I think I will start where the Prodigy manual suggests ... gain at 6.0 and boost at 2 and go from there.

We have returned from our first "road test" with the Montana and it was a great success. Went from the Hamilton, Ontario area to the Shadow Brook Campground in Cooperstown, NY. A wonderful spot, perfect weather, and a great first trip. On the return trip, Annie took the wheel and drove the rig from Niagara Falls, Ontario to our storage facility north of Hamilton. She did a great job and appeared less anxious about hauling a 37' building down the highway than I was!

Thanks again for all your assistance.

While I am hesitant to say so in public, it may be the case that "the light went on" with respect to my "grabby brake" situation. Since it is the purpose of "boost" (in my Prodigy system) to apply immediate braking while the unit senses deceleration, at very slow speeds (such as when I initially pull out of a camp site), any application of the brake will cause the boost to kick in and instantly stop the RV in its tracks ... which is exactly what happens. When I initially test the trailer brakes and hitch security using only the RV brakes, there is no grabbing. Once I get on the highway and apply the brakes when I have a bit of speed, the brakes on both the truck and the RV work perfectly ... no grabbing at all. 

Does this make sense ... or am I deluding myself into thinking I may actually understand what is happening?

Just now got logged on and we just got the truck set up yesterday so I'm really new,  but I thought I'd share this: While reading the Prodigy operating manual I saw they reccomend "warming up" the brakes with a little drag before you hit the highway.
Hi, BillD ...

I read the same thing ... which is what led to the grabby brake situation I described above. I tried very lightly touching the brakes but the RV brakes always grabbed. Unless I am advised that it is a bad idea, I have decided to restrict my "brake warm up" to slowly moving ahead  and then stopping the whole truck/RV rig just using the trailer brakes. Seems to me that ought to (a) assure that the trailer brakes are working, (b) assure that the hitch is properly latched, and (c) warm the trailer brakes. I also read that adjusting the power/gain should only be done when the rig is moving at a speed of at least 20 mph on a dry surface ... which suggests to me that fooling with the brakes at very low speed is not a good thing to do.

Of course, all this could totally wrong ... but just trying to understand the system, how it works, and how to make the appropriate adjustments.

When we had fifth wheels, I always made it a practice to gently apply the brakes as I left the campsite and, depending on results, a few more times on the park roads as well.  Preferably where the surface was dirt or gravel.  Some days it took 2-3 applications to get over the "grab" and I much preferred to do it when I was expecting it and where the wheels could skid easily if they locked.

You are right about the boost and the first application of the brakes. When leaving my drive after storage for awhile, the drive is downhill, I set boost to 1. Other wise it is grabby. Once down the drive and on the road it's up to 2 and about 8-9.

Note that "boost" applies every time you press the brake pedal - not just the first braking of the day.  Excessively high boost will cause grabbing and it will be especially noticeable at low speeds.  And it will be very noticeable if the brakes are damp and prone to grabbing anyway, as when you first start out for the day.  Reducing boost for that first brake application might well alleviate the early morning grab problem.
I think I am slowly beginning to grasp the concept. It is also likely that my grabby problem is because the techs that installed the system set the gain at "10". If boost 1 applies 13% of the gain immediately, that should be roughly equivalent to boost 2 (which supposedly applies 25% of the gain immediately) and a gain of 5.2. Methinks my next low speed test will be at a boost of 1 and a gain of about 5 - 6 for my initial brake application. The experimenting continues. I do feel more comfortable with an ultimate setting of gain around 7 - 8 and boost 2. Thanks again for the advice and counsel.

This happened to my dad and I two years ago. The brakes on the trailer would grab very hard to matter what. The problem was one of the wires on the trailer responsable for some part of the brake system had rubbed through the insulation and the wire was shorting out to the trailer frame.
Migth want to check that out if the problem occurs again.
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