Brakes locking up with BMW X3

[jpw159]

Hello. I recently purchased my first travel trailer, a 2008 Safari Sport 17 - and just love it! I intend to tow it with a 2005 BMW X3 with a class III hitch and OEM wiring harness installed. On my maiden voyage with the Safari / X3 combination this past week, I found that there is a major problem somewhere. When just barely tapping the breaks on the BMW, the Airstream brakes completely lock up causing a violent thud. After going around the block a few times trying to figure out the problem, I gave up and took the trip towed by family member's SUV's. This same trailer has been towed now by four other vehicles with no problem whatsoever, so I think there may be a problem with the BMW. Incorrent installation of he wiring harness? Do I need to install the Prodigy brake controller that the Airstream dealer sold me but did not install? Please help!

[2airishuman]

Originally Posted by jpw159

...Do I need to install the Prodigy brake controller that the Airstream dealer sold me but did not install? Please help!

hi jpw and welcome to the forums!

what brake controller is being used in lieu of the prodigy?

without a brake controller of some sort/brand/model,

the trailer brakes are NOT active or functioning, just because the wiring harness (7 pin) is connected.

so are u sure they "locked up" which should skid the tires and tug rearward on the bimmer...

or are you experiencing NO trailer brakes, which would BUMP the bimmer with the slightest brake application?

also most brake controllers require some calibration during set up...

basically this involves adjusting the gain/boost and

using the manual brake controller lever a few times to gauge trailer brake effectiveness.

i'm not sure this applies to the x3 but there are MANY threads here related to the wiring harness on euro tow vehicles...

mostly the issues are related to brake light functions and flicker,

and the fix involves an inline tweak to the wiring harness.

cheers
2air'

[Kajtek1]

Originally Posted by jpw159

I intend to tow it with a 2005 BMW X3 with a class III hitch and OEM wiring harness installed.

German cars do not supply brake controllers. I assume that you have brake light connected to brake light circuit and that is why the brakes lock.
You need to install brake controller. Meaning pulling 10 ga wire from main power supply and running new wire from the controller to the trailer plug.

[richinny]

welcome!

if the bmw is not currently using any controller, full power to the brakes will lock them up. the controller adjusts the amount of power needed to stop.

[RedSHED]

I'm going to guess that the wire on the trailer side that goes to electric brakes is, on the X3 side, connected to the brake lights.

Here's a link with a diagram: How to Wire your Car or Truck for Trailer Lights

To see if it's the "high beam" tail lights that are connected to the brake wire, I suppose you could get a multimeter and turn on the flashers...
It's German, though, so it might not be that simple.

Another thing you could try... hook the multimeter up to the X3's harness, stand on the brakes, note the result. Then try it with one of the tow vehicles that works, and compare results. I'm no expert, but would expect to see a current difference between the two.

Finally, if you don't have a brake controller installed, I don't know how you'd have brakes in the trailer.

Good luck, and I think we're going to need some pics. Sounds like a really nice setup!

[overlander63]

I repaired a trailer that the owner had wired his brake light wires to his electric brake wiring. When he stepped on the brakes, the trailer brakes would lock up. You may have a similar situation.

[Westfalia]

My thoughts exactly. You NEED to have a brake controller.

VW has tried to pull the same (poop) saying that the VW Touareg already had a supplied brake controller with the tow package, which was completely wrong and dangerous information. Also, consider using an Envoy, not a Prodigy. If your X3's electrics are anything like the Touareg, the Prodigy did always play well. My analog Envoy was plug and play. Best of luck.

[2airishuman]

while we are waiting for the o.p. to respond back, a couple of questions 2 those that know....

1. ?what a/s dealer would allow ANY CUSTOMER to leave the lot without a properly functioning brake controller?

-perhaps the initial tow was with the "family member's suv" that was properly equipped...

-perhaps that's why the a/s "sold" but didn't install the prodigy....

2. ? does the 7 pin wiring on the a/s trailer side SHARE brake lights and braking power in the SAME pin?

3. ? is the bmw oem wiring harness (which is installed later) a typical 7 pin or one of the many other flavors that needs an adapter?

cheers
2air'

and no offensive to the o.p. who may be very new to this whole process,

and not wanting to fuel yet another flaming tow vehicle exchange, but...

the x3 is rated to ~3500 max before payload reductions...

so even the 17 safari sport might be TOO MUCH 'STREAM for this car based mini suv...?

[jpw159]

Thanks everyone for your generous information. A couple of answers to some of your queries:
- No brake controler is currently in use. There was also no brake controller on any of the three other vehicles that towed the Safari (GMC, Ford, Jeep). They all tow it just fine - I'm not realy sure if they are causeing the Airstream's brakes to engage or not, but braking with each of them seems good.
- I won't name the A/S dealer who sold the Safari to me because it was a horendousely torturing experience and took almost two months to get the trailer. I'd like to drag their name through the mud for what they put me through, but I shant. In the end, they delivered it to me. They simply dropped off the Safari, the Prodigy, a weight distibuting hitch package, the wrong set of owners manuals, one set of keys, and a set of keys for someone elses 2007 25 ft. AirStream. No walk-though or support in getting everything started - double trouble because this is my first travel trailer. It was a mess. My brother in-law and I installed everything (except the Prodigy) and got everything working so far (except the 6-gallon water heater - any tips here?)
- Although there is no brake controller installed, the trailer brakes are most certainly locking up and it is not the trailer bumping up agaInst the X3. You can hear them screech if you're going fast enough and people outside of the tow vehicle witnessed it.
I'm going to try installing the brake controller and see if that helps. Interestingly, it seems that the BMW requires a different wiring scheme that most - the X5 forums are full of people discussing this issue. The BMW is definitley wired differently than the three domestic SUV's - when we used a meter to try and determine which pins were doing what - the BMW is not even close to the same as the others. The BMW pins were all constantly flowing current - even when the car was off. The domestic SUV's current only flowed when a light was on or when the brake was pressed.

I'd be interested to hear more about "...one of the many other flavors that need an adapter..." as mentioned. Maybe an adapter is all I need? Thanks agin to you all for the great info.

[Silvertwinkie]

You must have a brake controller to safely and legally tow a trailer of 3500lbs or more. If your brakes are engaging and you have no controller, I would think that you most likely have a wiring problem, maybe similar to what Overlander63 stated. If correctly connected and no brake controller, no brakes should activate.

[2airishuman]

Originally Posted by jpw159

- Although there is no brake controller installed, the trailer brakes are most certainly locking up and it is not the trailer bumping up agaInst the X3. You can hear them screech if you're going fast enough and people outside of the tow vehicle witnessed it...

OK GOOD INFO! jpw...

it's unfortunate to read about the awful dealer/buying experience.

without a controller and with power to the brake wire the result seems to be FULL ON braking with any current.

except for vehicles with integrated brake controllers (some ford trucks and some from the other guy)...

i've never heard of or read about anyone towing with the trailer brakes connected, but NO controller.

so who's idea was it to take this approach of no brake controller?

with a small enough trailer and large enough tv NO trailer brakes can be ok in some situations....

but u clearly NEED that prodigy installed, calibrated and functioning.

for some reading about the euro wiring harness issues and corrections,

search devoman's posts (he tows with a t-rex) or

dpeakmd (he tows with an x5) i think they have both covered the harness issue...

cheers
2air'

[ROBERTSUNRUS]

Hi, my wife owns a BMW X3 [2.5L] and I would not tow anything with it. As for the German wireing, How many cars do you know of that have a single filiment bulb [1156] that serves as the tail light bulb and the brake light bulb together? Evidently it has lower voltage or a resister to run this bulb as a tail light and full power to run the same bulb as a brake light. Not to mention it has a second set of brake lights that are supposed to come on with really hard braking or panic stops. [I have not seen these come on yet] I have worked on American, Japanese, and German Ford products and have not seen anything wired like this. You definately need to know the proper way to hook up a brake controller on this vehicle. Better yet get a more capable tow vehicle to install the brake controller in and to tow with.

[ROBERTSUNRUS]

Hi, in this picture my wife is going to tow my Navigator and Safari with her BMW X3. Also with California license plates you don't need head lights at night.






Actually, tomorrow is street sweeper day so I have remove my fleet from the street.

[millvalleyca]

Hi JP
I would suggest taking the trailer to a different AS dealer to make sure you're hooking everything up correctly. I would also contact Airstream to complain about the dealer that sold the AS to you assuming it was an authorized Airstream dealer.
Good luck...you're gonna love Airstreaming.
Dennis

[Road Ruler]

From what I have read the X3 is an excellant TV for many Airstreams and the wiring in not a big issue.

Stable TV + appropriate connection + stable TT = fine ride

[mustang]

Dont controlers have adjst ments For amout of power and aply timeing like a delay?

[Wisco]

We also have an '05 X5, though we use my F250 we like to have our options available. Here is some info that may help others, for future reference, on how to install the Tekonsha Prodigy.

http://www.bmwmotorsports.org/pdf/BM...er%20Brake.pdf
http://www.bmwmotorsports.org/pdf/X5...stallation.pdf