Trailer wiring Harness - HELP! - Land Rovers Only

One and All · 08-28-2007, 04:59 PM

I bought an original Land Rover trailer harness which I installed on my vehicle (Range Rover 4.0SE – 1995) last week. The adapter gives me a connection to my trailer with the supplied adapter (7 round) to a flat 5 pin connector. I worked out the correct pin on the vehicle side connector to connect the 5th BLUE wire and then into the adapter and hence the trailer, but the blue wire doesn’t connect to anything on the vehicle side……….!

In fact there are 3 wires on the bit of the harness that is in the right hand side access panel at the rear of the cargo space - (a red, an orange as well as the blue wire). They don’t connect to anything and the instructions don’t say to what they should be connected!

My problem is that I can’t back up / reverse with the trailer & my 5000lb boat because the blue wire has to be connected to disengage the trailer brakes. The trailer has a hydraulic brake actuator and I guess somehow the vehicle has to electronically tell the trailer when it is has to reverse. Otherwise the trailer brakes go on.

Any ideas where these 3 wires should be connected?

nzoliver · 11-12-2007, 01:56 PM

Howdy,
I'm sure 1 of the 3 separate wires not in the main round plug will be reverse. I did this experiment when I wired my Disco. trun the ign on and select reverse and stick a multimeter or light accross them untill you find it.

My 10c

stolenheron · 11-12-2007, 02:10 PM

I had this happen to me once when I had to rewire my boat trailer and my acura MDX harness. and sadly, I don't remember what the hell we ended up doing....

I gotta go buy a trailer harness for my rover...can't wait to face this problem lol

Discoandaboat · 11-13-2007, 02:37 PM

from what remember...
The extra wire(not connected) is for the reverse lock out on my boat trailer. I have to turn my connector sideways so only 1 pin from the truck is going into 1 going on the trailer and then turn my lights on. I think its the blue to the brown wire??? It deactivates the brake lock out. Not sure if this even helps!

CincyDisco · 02-01-2008, 11:37 AM

Same problem here. I didn't find this until after I posted mine. did you ever figure it out?

stolenheron · 02-19-2008, 10:34 AM

lol i ordered my atlantic british wiring harness today, let the install confusion begin!

XtremeMarine · 02-19-2008, 01:39 PM

The last few I've done for customers (not Rovers) all had the brake disengage wire, spliced to the reverse light wire of the host vehicle. When the vehicle engages reverse, and 12v power goes to the reverse lights, it powers the pin which sends a signal to disengage the trailer brakes. Your Blue in this case, if I read right. The brown would be to a frame ground, and the orange has me stumped. I also rewire and repair trailers as part of my business, so I face this usually monthly.

08-28-2007, 04:59 PM	#1 (permalink)
One and All Member Join Date: Aug 2007 Location: Miami Posts: 1 Gallery: 0	Trailer wiring Harness - HELP! I bought an original Land Rover trailer harness which I installed on my vehicle (Range Rover 4.0SE – 1995) last week. The adapter gives me a connection to my trailer with the supplied adapter (7 round) to a flat 5 pin connector. I worked out the correct pin on the vehicle side connector to connect the 5th BLUE wire and then into the adapter and hence the trailer, but the blue wire doesn’t connect to anything on the vehicle side……….! In fact there are 3 wires on the bit of the harness that is in the right hand side access panel at the rear of the cargo space - (a red, an orange as well as the blue wire). They don’t connect to anything and the instructions don’t say to what they should be connected! My problem is that I can’t back up / reverse with the trailer & my 5000lb boat because the blue wire has to be connected to disengage the trailer brakes. The trailer has a hydraulic brake actuator and I guess somehow the vehicle has to electronically tell the trailer when it is has to reverse. Otherwise the trailer brakes go on. Any ideas where these 3 wires should be connected?

11-12-2007, 02:10 PM	#3 (permalink)
stolenheron 2004 Discovery II driver Join Date: Jun 2007 Location: Fort Myers, Florida Posts: 1,577 Gallery: 6	I had this happen to me once when I had to rewire my boat trailer and my acura MDX harness. and sadly, I don't remember what the hell we ended up doing.... I gotta go buy a trailer harness for my rover...can't wait to face this problem lol __________________ 2004 Discovery II SE7 - My Ride 2006 LR3 SE - Dad's Ride

02-19-2008, 10:34 AM	#6 (permalink)
stolenheron 2004 Discovery II driver Join Date: Jun 2007 Location: Fort Myers, Florida Posts: 1,577 Gallery: 6	lol i ordered my atlantic british wiring harness today, let the install confusion begin! __________________ 2004 Discovery II SE7 - My Ride 2006 LR3 SE - Dad's Ride

02-19-2008, 01:39 PM	#7 (permalink)
XtremeMarine Senior Member Join Date: May 2007 Posts: 1,590 Gallery: 0	The last few I've done for customers (not Rovers) all had the brake disengage wire, spliced to the reverse light wire of the host vehicle. When the vehicle engages reverse, and 12v power goes to the reverse lights, it powers the pin which sends a signal to disengage the trailer brakes. Your Blue in this case, if I read right. The brown would be to a frame ground, and the orange has me stumped. I also rewire and repair trailers as part of my business, so I face this usually monthly. __________________ "In certain places, at certain hours, gazing at the sea is dangerous. It is what looking at a woman sometimes is." - Victor Hugo Originally Posted by Elemental Some guys play hard to get, I play hard to want.

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11-12-2007, 01:56 PM	#2 (permalink)
nzoliver Member Join Date: Aug 2005 Location: Lake Tekapo, New Zealand Posts: 56 Gallery: 5	Howdy, I'm sure 1 of the 3 separate wires not in the main round plug will be reverse. I did this experiment when I wired my Disco. trun the ign on and select reverse and stick a multimeter or light accross them untill you find it. My 10c

11-13-2007, 02:37 PM	#4 (permalink)
Discoandaboat Member Join Date: Mar 2007 Posts: 82 Gallery: 0	from what remember... The extra wire(not connected) is for the reverse lock out on my boat trailer. I have to turn my connector sideways so only 1 pin from the truck is going into 1 going on the trailer and then turn my lights on. I think its the blue to the brown wire??? It deactivates the brake lock out. Not sure if this even helps!

02-01-2008, 11:37 AM	#5 (permalink)
CincyDisco Member Join Date: Jan 2008 Location: Cincinnati Posts: 15 Gallery: 0	Same problem here. I didn't find this until after I posted mine. did you ever figure it out?

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