Trailer wiring - Pin count & electronic brakes

aaroncat · #1 12-06-2009, 12:46 AM

Hi all,

I don't usually have to post questions as everything I need has been covered. Even this question has been covered but not from the angle (and with the simplicity) I am looking for, so I am hoping someone can help me out

I have a trailer with electronic brakes that has a 5-pin flat connector (the 5th pin is used to control the electronic trailer brakes). It is the same connection as this device has: http://www.denlorstools.com/shop/ima..._Tester_lg.jpg).

I have an 07 X5 that I am about to get the OEM hitch installed on by the dealer and had 2 questions:

1. What is the wiring receiver style used on the BMW hitch? I tried to find a picture of the receiver on the forums but failed. Is it the 7-pin RV-style like this: http://www.corndogg-offroad.com/trailers/7pinplug2.JPG ? A picture would be great if anyone has the hitch installed (I found plenty of pics but the dust cover is always closed hiding the pin layout)!

2. If it is a 7-pin female plug does anyone have experience with 7-pin to 5-pin flat adaptors like shown here: TRAILER RECEPTACLES AND PLUGS (Part# I-725) ?. My main concern is that the 5th pin being hooked up (I believe most people splice it into reversing lights on vehicle - but I am hoping maybe the adaptor already takes car of this) is necessary to turn the electronic trailer brakes off. Without it, reversing is impossible without overriding the braking mechanism manually.

I am destined to find out my answers soon (through a few reversing attempts after the hitch is installed) but my goal here is to find out if I need to give the dealer any special instructions on giving me this 5th wire capability.

Cheers,
Aaron

FunfDreisig · #2 12-06-2009, 08:22 AM

The BMW OEM hitch wiring comes with the 7 pin RV style connector (behind the dust cover) AND a 7 pin RV style to 5 pin flat trailer adapter similar to the ones you linked.

FWIW I'm not sure if the 7-5 adapter that comes with the hitch is wired for electric brakes, because my trailer uses the 6 pin round connection.

Funf Dreisig

p.s. I'd be happy to map the pin outs on the 7pin-5 pin adapter if that would help you.

aaroncat · #3 12-06-2009, 02:22 PM

Thanks for the reply FunfDreisig, I appreciate it

This is awesome news, I would hope that BMW were intelligent enough to hook up that 5th wire if they provide us with the 7-pin to 5-pin adaptor.

Thanks for the p.s offer but I think this is all I needed to know. Looks like the dealer has me covered.

Cheers!

mikewaterskis · #4 12-07-2009, 08:28 PM

We have a 2005 X3 and I do tow my boat with it at times and that trailer needs the 5th wire to release the brake to make it back up...

It was dealer installed hitch & wire

let us know how you make out... <hoping to have a X5 in near soon!!!

aaroncat · #5 12-08-2009, 12:12 AM

Thats good to know Mike, this is the exact reason I am asking. Our trailer refuses to budge without power on that 5th pin.

How much does your boat weigh? and how does the 3.0L go towing it?

I estimate our boat (Outback V) with trailer is about 4000-4200lbs and am worried about our 3.0L lugging it around in the future.

mikewaterskis · #6 12-08-2009, 12:29 AM

I'm about the same weight with my Ski Nautique 196 ... It tows it ok but I mostly only tow 3 miles and thats mostly though our housing development plus I'm in Florida (flat land no big hills) I have towed 200 mile (one way) trips with it and it tows it ok but I wish it was bigger and had more power but it works..
The only problem I have is that I have LED lights on the trailer and they don't like the BMW lights so they blink when it is hooked up even when off and locked up...

next will be a X5 or the new X3 if its bigger in about 18months for me..

aaroncat · #7 12-08-2009, 04:53 PM

Yeh, we have LEDs on our trailer also. What exactly is it that blinks? An interior warning or the LED lights on the trailer? You've got me worried now. Does it look like you've got your hazards on the whole way down the road?

mikewaterskis · #8 12-09-2009, 10:50 PM

Aaron the LED lights on the trailer will blink twice than stop for couple of sec than blink twice again... and the turn sign will blink fast at times... This does not happen on my Silverado and I don't know if I ever saw it happen to anyone else either but I did hear that bmw does have this problem I think its something to do with the relays on the car.. Mine is a 2005 maybe it will be better with a newer car but I wouldn't worry about it.. Let me know how you make out...