Boatless Trailer Towing Problem

[Shoemaker Mobius]

Help!!! Last night, for the first time since we purchased our 2004 Mobius LSV, I trailered the boat to our normal launch and let my son and his friends take the boat out by themselves. Since I don't feel comfortable with my son's driving and backing abilities with the car and trailer, I drove to the launch ramp, helped him launch the boat and then I drove home with the empty trailer. The plan was that about 4 hours later I would drive back to the launch ramp and pick him and the boat up. So, I had never driven any real distance with the trailer empty. The trailer is the standard Boatmate trailer, single axle, no swing away tongue, just the straight one. Here's the problem. The drive from the launch ramp to my home is about 20 miles of highway/city type driving. On the highway, while the trailer felt a little loose, it was no problem. However, several times toward the end of my journey, when braking to come to a stop, from about the 20-10mph range down to the final stop, the trailer would begin to buck violently, enough to actually shake the entire car (a 2wd Ford Explorer). It scared the devil out of me and my wife. After it did it the first time, I began driving much slower and trying to ease into braking, but that seemed to actually make it worse. We were able to get home and immediately called the dealer to find out what to do. The service manager tried to be helpful, but basically he indicated that the trailers were not meant to be towed long distances without the weight of the boat on them; that the trailer brakes were activating and we were experiencing "brake chatter". He said he had gotten a lot of complaints about this. He said that the way the trailer worked was the trailer brakes were engaging as they were supposed to, but because the trailer was empty, the brakes on the trailer engaged as if they were stopping the fully weighted trailer which would then cause the trailer to buck. He indicated that there really was nothing that could be done, but suggested that I deinflate the tires approx. 10 psi below the psi posted on the tires, that that would help. I asked him if as I braked, if I released my car brakes would that release the trailer brake. His answer was no, that the trailer brakes are activated by the coupler on the tongue, that as the trailer pushes toward the car, the coupler closes and engages the trailer brakes (i.e., they are not at all activated by my car's brakes).

For the return trip, I did deflate the tires to about 50psi. I also decided that as approaching a stop, I would brake hard, then release and ease up to the stop. That seemed to be better. One thing of note was that when the trailer was bucking, I could see in the mirrors that the wheels were rolling - the first time it did it I was afraid that the trailer brakes had locked and the tires were just dragging and bouncing along the road, but that was not the case. Given that I was trying to control my car and praying the violent bucking was not going to just rip the trailer and my hitch off the car, I could not just constantly watch the tires to see if they were always rolling, but they did seem to be. I did not see any skid marks on the road and the tires did not seem to have any skid type indications on them. Also, I did verify that the hubs were still full of oil and intact.

So, has anyone else had this happen? Is this really just the way it is? If so, I will never tow this trailer any appreciable distance without the boat on it. With the boat on the trailer I have never had any problems at all. Please let me know.

[Yellowmobius]

One way you might get around this would be to flip your trailer light connector and turn on your parking lights, this will get power to the brake actuator and effectively disengage the brakes. It is hard to explain what I mean by flipping the connector over, you basically have the one pin that would not be connected. This will affect how the trailer lights work. It is the same thing you do to disengage the brakes if you do not have the 5th wire harness.

[Shoemaker Mobius]

Bruce,
I think I know what you mean, but I don't understand the impact and why I would need to turn on the parking lights. If I understand correctly, my trailer wire connector has 5 pins; the connector on my car has one male and four female connections on my 5 wire connector; the connector on the boat has one female and four male connections on the 5 wire connector. I am guessing that the single connection has something to do with the trailer brakes? So, if I turn one of the 5 wire connectors upside down that would mean I would only be able to plug in the four connections with one connection hanging off the plug. Correct? Also, I can see then that the four connections would be reversed (i.e., with the connectors aligned correctly, 1-2-3-4-5 would be connected to 1-2-3-4-5 with the 1 being the single plug). However, with one connector upside down, the connections would be 1 to nothing, 2 to 5, 3 to 4, 4 to 3, 5 to 2 and 1 to nothing. If that's correct, I don't see how the trailer lights would function anywhere near correctly. I am assuming that the main 4 pins connect left turn signal, right turn signal, brake lights and tail lights. If you changed the order, when you hit your left turn signal, wouldn't your tail lights or brake lights go on then and if you had your headlights on, wouldn't conceivably one of your turn signal lights on the trailer blink continuously? I'm nowhere near a mechanic or electrical guy, but it seems that just wouldn't work. Can you explain further??? Thanks.

[Yellowmobius]

Your understanding of what I mean by flipping the connector is correct.
I am not sure how the trailer lights will work, try it and see. It won't hurt anything, but they will not work correctly, obviously.

This is my understanding of how the brake actuator works.
When you back up or step on the brakes the actuator collapses and engages the brakes.
The key is "when you back up". When you back up the brakes are engaged without the 5th wire. The 5th wire gets power from your reverse light wire effectively disengaging the brakes. Try backing up with out your lights connected you will understand. When you filp the connector over you are lining the trailer marker light wire up with the brake disengage wire by turning your lights on you are powering the brake wire and disengaging it.

I had to do that when I first bought my boat because my truck only had a 4 wire connector and the salesman told me that is what I had to do. He actually said "they don't make a five wire connnector" The boatmate guys hooked me up!

Later

[Shoemaker Mobius]

Thanks, Bruce, that makes sense. Unfortunately, I just tried the flip and the results were that the car's left turn signal turns on the trailer's right turn signal and likewise the car's right turn signal turns on the trailer's left turn signal. The brake lights seem to work OK, but the the tail lights don't turn on when the headlights are on. Overall, the light reversal is probably as much of a hazard as the trailer itself. I took the boat and trailer in to the dealer today and he is going to inspect the brakes to make sure they are working correctly. Have you or anyone else had this problem with towing an empty trailer??

[Yellowmobius]

I have never towed empty.
With the connector flipped you won't get trailer lights because that power is now going to the brake and the blinkers being reversed sounds right.
You are right that is not the safest way to drive either.

[Wake Master]

You can also place the brake key in the trailer tounge to deactivate the trailer brakes. The one that came with the trailer will fall out easy, so you would need to find something to keep it in place. My dealer had a key that was kept in place by mounting over the top of the tounge

[carsondoc]

Shoe, I like Wake Master's idea for disengaging the trailer brakes on this one. You obviously don't need the trailer brakes when the boat's not on the trailer and they are probably the culprit. You just need to find a way to keep the key in there. (my first thought was duct tape--as always )

Please let us know if you do this, how you secured the key, and how it worked. Definitely good info for all of us as I'm sure we'll all need to tow without the boat someday.

[Shoemaker Mobius]

Wake Master,
What is a "brake key"? I don't see a way to deactivate the brakes on the trailer. Can you give me more information?? Is it something that keeps the sliding part of the trailer tongue from sliding? It is my understanding that the trailer brakes are activated by the coupler sliding mechanism moving towards the car, thereby activating the brakes. That's why the 5th pin on the wiring coupler is energized by the backup lights on the car, thereby overriding the trailer brake activation so you can back the trailer up.

[Woopededoo]

You should of gotten the key when you got the boat. Looks like a the letter 'D" with a little piece sticking off the side of it. It fits in the side of the trailer tongue where that one bolt slides back and forth, making it not be able to move. Mine was in the moomba bag I got with my boat that had all the manuals and extra stuff for the boat.

However, I still havent figuered out how to used it correctly. It falls out way to easy. And if you use it to put the boat in the water, you could easily loose it in it in the water.


Since my truck does not have a 5th wire, only 4. I take the 5th plug on the trailer plug, and attach it to the 1st plug on the truck (the headlights). So, when I want to put my boat in the water (back it up). I swap the plug, turn on the headlights and back up. However, this will make all the lights/blinkers not work on the trailer. When I am ready to go home, I just put the plug back to normal, just leaving the 5th plug exposed. The brakes on the trailer work all the time, except when you put some power to them, then they disengage.