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  #1  
Old January 5th, 2014, 08:27 PM
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Sam Odio
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Trailer wiring help

I'm trying to wire up a 7 pin plug on my defender (to hook up a new 16" airstream trailer).

Looking back there I found this plug with 7 wires coming out of it. It was connected to a trailer module which was then connected to a 4 ping plug.

I'm wondering - can I just wire my 7 pin plug directly to these 7 wires? All the colors match up. I don't want to short anything out so I thought I'd ask first.
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  #2  
Old January 5th, 2014, 08:30 PM
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Sam Odio
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Also, while I was in there, I saw these two wires just hanging not connected to anything. Anyone know what they might be?

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  #3  
Old January 6th, 2014, 01:28 PM
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Sam Odio
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Any help? Can someone at least tell me whether this is aftermarket or a standard plug?
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  #4  
Old January 6th, 2014, 01:37 PM
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I am not sure what connector an airstream uses (I assume brakes), but the rover 7 pin does not include brakes which is why you have the 7 to 4 flat converter. The stock rover wiring only gives you lights.

You need a brake controller and need to wire that in as well.
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Old January 7th, 2014, 01:07 AM
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Sam Odio
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Alright I'm going to go ahead and wire the 7 pin directly to this harness. I have an aftermarket brake controller so I'll go ahead and wire that in as well.
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  #6  
Old January 7th, 2014, 01:50 AM
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Quote:
Originally Posted by sro View Post
Alright I'm going to go ahead and wire the 7 pin directly to this harness. I have an aftermarket brake controller so I'll go ahead and wire that in as well.
Not going to work. Land rovers have separate stop and taillights which is why you have the converter to four flat. What year is your airstream? What are the seven wires you need? Reverse, left, right, taillights, ground, brake control?, auxiliary?
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  #7  
Old January 7th, 2014, 04:57 AM
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Ben Jones
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They look like UK 7 pin trailer colours.

Over here they are:

Pin - Colour - Function

1. Yellow - n/s indicator
2. Blue - fog
3. White - earth
4. Green - o/s indicator
5. Brown - o/s tail light
6. Red - brakes
7. Black - n/s tail light & number plate

Not sure if that's any assistance? The thing to do is put a multimeter on each of the pins / wires as you activate them see if you get a feed.

i.e. put a multimeter on to the red wire on the harness (before the converter plug/socket), get someone to stand on your brake peddle and see if you get a 12v feed.

NB. Don't forget that our n/s and yours differ! lol

Best of luck
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  #8  
Old January 7th, 2014, 08:03 AM
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Tom Rowe
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I haven't wired my D90 for towing with brakes, but have on both of the Disco's. Here's how I did it. Obviously some differences, but it should point you in the right direction.
http://landroverforums.com/forum/dis...29/#post179231
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  #9  
Old January 7th, 2014, 10:06 AM
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Sam Odio
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Okay, this is the pin wiring diagram for the airstream:



It looks like I need to connect:

- Black - 12V
- Brown, right turn signal
- Blue, aftermarket brake controller
- Red, left turn
- White, listed as 12V but I think that's a typo (probably ground)
- Green, clearance lights

It seems like this should work without a 4 pin adapter or anything other than the 7 pin coupler. I just need to wire the turn signals and running lights directly from the harness in the photo (after testing with a voltmeter of course).

The ground goes to the chassis and 12V from the battery. My plan is to put a 40A fuse on the 12v lead (http://www.etrailer.com/question-44650.html).

Am I missing anything?
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  #10  
Old January 7th, 2014, 10:34 AM
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I'm guessing your trailer has combined brake and turn signal lights. As evilfij said, since the Defender has separate brake and turn signal lights, you need to keep the four pjn connector in your system. You can then buy a 7 pin converter. I've set mine up that way.

For fuse size, check with your brake controller. I use a ProdigyRF and it specified more than 20 amps, so I went with 30 amps.
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Old January 7th, 2014, 03:02 PM
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Sam Odio
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I see, so the right turn and left turn in the wiring diagram also serve as the brake lights. Makes sense now.
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  #12  
Old January 8th, 2014, 11:30 AM
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Tom Rowe
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You want a self resetting circuit breaker for the brakes, not a fuse. If you have a fault you want at least intermittent brakes until you can pull over and sort it out.

CA (and most states) if your trailer has brakes you're required to have a break-a-way controller on the trailer. Plus it's polite to other users of the road. That battery would be powered by the aux always hot 12v wire, probably the purple one in your photo.
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Tom Rowe
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Four wheel drive allows you to get stuck
in places even more inaccessible.

62 88 Regular
67 109 6cyl NADA x2
74 Lightweight - The Antichrist
95 DI 5-speed
95 D90 5-speed
97 D1 Automatic
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  #13  
Old January 8th, 2014, 12:00 PM
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Chris
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Those extra green wire is a constant 12 feed to support the battery in the "caravan" (aka RV)
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A friend of mine runs a land rover / range rover specialty repair shop. Based on his experience, they are capable of stopping anywhere, anytime, at any cost.

I don't know about the brakes, only their unreliability.
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  #14  
Old January 8th, 2014, 12:50 PM
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Sam Odio
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Quote:
Originally Posted by Antichrist View Post
You want a self resetting circuit breaker for the brakes, not a fuse. If you have a fault you want at least intermittent brakes until you can pull over and sort it out.

CA (and most states) if your trailer has brakes you're required to have a break-a-way controller on the trailer. Plus it's polite to other users of the road. That battery would be powered by the aux always hot 12v wire, probably the purple one in your photo.
Good to know. I'll get a self-resetting fuse. Already have a break away on the trailer.
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  #15  
Old January 8th, 2014, 02:21 PM
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Bob Vogler
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Quote:
Originally Posted by Antichrist View Post
You want a self resetting circuit breaker for the brakes, not a fuse. If you have a fault you want at least intermittent brakes until you can pull over and sort it out.

CA (and most states) if your trailer has brakes you're required to have a break-a-way controller on the trailer. Plus it's polite to other users of the road. That battery would be powered by the aux always hot 12v wire, probably the purple one in your photo.
One correction, from someone who's already made every possible towing mistake over the years: the breakaway switch should be powered either by the trailer battery or its own battery (if the trailer has no battery), not by the hot wire from the tow vehicle. If the trailer "breaks away," you'd need a really, really long purple wire to operate the breakaway switch!
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  #16  
Old January 8th, 2014, 06:54 PM
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Quote:
Originally Posted by 2411D90 View Post
One correction, from someone who's already made every possible towing mistake over the years: the breakaway switch should be powered either by the trailer battery or its own battery (if the trailer has no battery), not by the hot wire from the tow vehicle. If the trailer "breaks away," you'd need a really, really long purple wire to operate the breakaway switch!
All breakaway kits come with a small AGM battery (that lives on the trailer) and switch to activate it. The constant 12v from the tow vehicle is to keep the battery charged.

Also, always connect the break-a-way switch before connecting the trailer plug to the tow vehicle. Some controllers can be damaged if you engage the trailer brakes (while hooking up the wire to activate the break-a-way switch) while the trailer wiring is plugged in to the tow vehicle.
Not all are like that, my Tekonsha isn't, but it's a good habit to be in.
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Tom Rowe
Atlanta, GA

Four wheel drive allows you to get stuck
in places even more inaccessible.

62 88 Regular
67 109 6cyl NADA x2
74 Lightweight - The Antichrist
95 DI 5-speed
95 D90 5-speed
97 D1 Automatic
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  #17  
Old January 11th, 2014, 09:08 AM
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Sam Odio
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Okay, so I ordered a 5 to 4 wire converter for the trailer lights / brakes.

I also ordered 25 ft' of #4 cable for the charging circuit (both Black - 12v and White - ground). Quick question before I hook all this up: how can I make sure the #4 charging cable doesn't trip the 40A fuse when the trailer batteries are being charged by my 120 amp alternator?
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  #18  
Old January 11th, 2014, 11:08 AM
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Sam Odio
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Okay, just purchased a bambi 16! Very excited. I plan on using it for extensive boondocking.

Based on this forum, I'm about to install the following:
  • 5 to 4 wire trailer brake light controller
  • 40A charging cable (#4AWG) from TV to airstream with 50A SMH connector
  • 7 pin trailer connector
  • Running 4AWG cable for solar (which isn't yet installed).
  • Installing two 6V batteries (eventually upgrading to 4)

Here's the circuit diagram: https://www.dropbox.com/s/fht48aknqh...g-charging.png

Can anyone see any huge mistakes? Open questions:
  • I'm currently running two connectors to the airstream: a high-gauge cable (pos and ground) and the regular 7 pin connector. Should I scrap the high-amp SMH connector?
  • For faster recharging the alternator battery sense is running off the second 12V battery that's on the vehicle (this will often stay connected to the airstream and drain with the airstream). Bad idea?
  • Second battery will be connected to starter battery when ignition is on so I figure even if the starter battery is low (due to no battery sense) the second battery should be able to start the vehicle.
  • Running lots of 4AWG cable (do I need it all?)
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  #19  
Old January 12th, 2014, 12:17 PM
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I can't speak for much of it off the top of my head (see what happens when you don't use an EE degree for 25 years?), but the 4AWG wire is a waste in most of your connections. The solar connector is only 68 W, or about 5 A @ 12 V - unless you have a run of 500 feet, that's complete overkill. The others are similar. Here's an automotive wire calculator:

http://www.gtsparkplugs.com/WireSizeCalc.html

Save a bit of cash -and- it's a lot easier to run smaller wire.
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  #20  
Old January 14th, 2014, 01:18 AM
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Sam Odio
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Thanks. That's helpful.
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