This is serious stuff to me and I and asking for serious replys from the people that I know that have the most knowledge.
I own a 1968 Tradewind 24' dual axel Airstream with electric brakes. My tow vehicle is a 2006 Ford F-250 6.0 Powerstroke turbo diesel with a factory tow package.
The tow package brake controller showed all green the past three time we went camping, including the start of this trip.
I wired the Airstream to the tow vehicle myself and checked all the functions. Everything worked A-OK.
We had three uneventful camping trip of 360 miles round trip each with this TT /TV combo.
During our latest trip, while driving at moderate speeds (20 to 30 mph) in city traffic, I manually turned on the parking lights / headlights. And all hell broke loose.
The Airstream's electric brakes locked up in a cloud of smoke. The tow vehicle schuttered. thank goodness no one was behind me.
I immediately turned off the lights and the Airstream's brakes released. What the heck! When I turned the parking light / headlight off and all was well.
I pulled the Airstream's wiring harness 7 plug coupler and found that the black (ground) wire was very loose. I re-connected the black wire and everything worked properly.
I noted that the black wire was strained to reach the 7 plug Airstream terminal in the harness wiring, which may have cause the black wire to work loose.
This fix is not good enough when my wife or other people are involved.
I have researched the problem without good result.
Question #1
Can a loose black ground wire cause the electric brakes on a 1968 Airstream to lock up. Or is there another factor to look at.
I will not gamble with other people's lives, or with my wife's. How can I tell / trouble shoot the cause of the trailer brakes locking up with an OVM to make sure my observations are correct.
Please check the continuity of the wiring in the trailer. With the vintage of the vehicle, it may have chaffed in some area allowing the running lights to power the brake system, causing your brake lock up on the AS. I had this problem earlier this summer and found my problem was chaffed (not completely broken) wires on the tongue. Good luck!
Check to make sure you dont have a burnt out bulb in the brake lights on the truck, or that the sockets for the bulbs aren't corroded.
Fords get a little wonky when determining if the brakes are activiated if the bulbs are burnt out. This is usually noticed when the cruise controll starts acting funny when the running lights are on.
Other than that, the loose ground wire would make sense as a culprit if your trailer uses the combination brake and tail bulbs. (the bulb with 2 filaments).
The expected current path when turning on the tail lights, is 12V through the tail-light Filament to the truck ground via the ground wire on the connector.
The 2 filaments are tied at thier grounds, So if the ground connector is open then the current path would be through the tail-light filament then through the brake-light filament. This means there is now +12v on the brake light circuit .(for my fellow EE geeks, think pull-up resistor) This could trigger the brake controller to think that the brake lights are on. Therefore it thinks the brakes are applied.
If its an inertial sensor, its going to detect that the rig is not slowing down, therefore it applies more power to the brake circuit, which causes them to lock up.
Even with the ground wire totally disconnect, the problem may be sporadic, since the hitch and ball provides a unreliable ground path back to the truck.
You might be able to run some tests in an empty parking lot for peace of mind.
Drive the rig with the the ground wire disconnected at the plug and turn on your lights.
If the trailer brakes lock up then reconnect the ground wire and repeat step one.
If the trailer brakes do not lock up, then we are all either way offbase, or thier is enough current flow through the ball & hitch.
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Champagne wishes and Caviar dreams!
Budwieser budget.
VOLVOPHILE your reply is excelent , but I am suprised that the light bulbs survived a 12amp load placed on them by the brake coils (lock up) ,unless there was also another (additional) route for a back feed.
drive safe
you cannot force 12amps through an electrical circuit without putting stress on the components, sooo don't be suprised if light bulbs or other components brake down or burn up.
drive safe
...During our latest trip, while driving at moderate speeds (20 to 30 mph) in city traffic, I manually turned on the parking lights / headlights. And all hell broke loose...I immediately turned off the lights and the Airstream's brakes released. What the heck! When I turned the parking light / headlight off and all was well.
I pulled the Airstream's wiring harness 7 plug coupler and found that the black (ground) wire was very loose. I re-connected the black wire and everything worked properly....
The PO of my '78 Sovereign made his own umbilical - when I hooked it up to my E-350 Cabriolet Diesel a bunch of things went wrong.
A long afternoon on a rainy Wally World parking lot revealed that the trailer side strain reliever had been over tightened, effectively shorting out three of the circuits - could be that a similar problem is happening to you.
I detect that your umbilical MAY be too short - or that it was at least it was over-tensioned to cause the ground wire failure.
It is obvious that, at that particular time you turned the lights on, there was a current flow from the light circuit to the brake circuit.
I would recommend either replacing the umbilical or remanufacturing your existing umbilical assembly with new wire, or remanufacturing with the existing wire (if it is long enough to cut a foot or so off of either end AND you are sure there is no internal damage to the wire) to insure that none of the wires are shorting out internally.
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Dennis
"Suck it up, spend the bucks, do it right the first time."
Thanks so much to everyone for your suggestions. Ya'll are such a great pool of knowledge. Many things were brought up that I had not thought about.
Here, briefly, are the troubleshooting tests I conducted.
I've tested and re-tested my trailer's braking activation problem by ensuring there was no obvious shorts due to one or more strands of different wires accidentially "touching".
I tested several different wiring circuit fault possibilities by disconnecting different wires, then by driving on adjacent slow speed roads, towing my Airstream, while turning on and off the headlights of my TV. (I'm surprised deputies have not been called.)
The fault would only occurr when I turned on my parking light. Headlight activation was secondary to parking light activation and had no part in trailer brake activation.
The trailer brake activation only occurred when the black ground wire was very, very loose.
My trailer light lead cable is 'just" long enough to reach the TV connector.
That is not good and could be a source of the problem, but the trailer brake activation occurred during straight level towing, not during turns, tight turns or going up or down hills. hummm
I then stripped back the outer covering of my trailer lead wiring cable. I discovered that several of the seven interior wire insulators had multiple cracks/breaks in their insulator covering.
This may or may not have be the cause of the trailer braking activation when the parking lights were turned on, but it sure showed me that the trailer lead wire wiring harness was aged and faulty and needs to be replaced.
With the trailer wiring harness' black ground wire firmly in place in the 7 plug socket, I could not make the trailer brakes erantly activate under any condition.
I tried to research how a 1968 Airstream 24' Tradewind's lead wiring harness is connected, but I could not find an exploded diagram showing the path / terminal / layout.
At this point I am thinking about hiring a professional to re-wire the trailer lead wiring harness.
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