Trailer Wiring Harness Installation
Range Rover
Mark III/L322
Introduction
Factory Wiring Harness Details
Removing the Loadspace Trim
Panels
Routing
& Securing the Wiring Harness
Connections to Rear Fusebox
Reassembly
Parts & Sources
More Information
Photo at Right: 7-Pin
Trailer Connector safely installed on author's 2004 Range Rover
Introduction
Land Rover is gradually catching up with its competition in the matter
of towing harnesses. For the first time on a new Range Rover model,
there is finally a
factory wiring harness for the RR III/L322/LM with North American spec
7-pin and 4-pin plugs.
It costs about $200, including an ECU and a relay that plugs into the
rear fusebox. This page covers the installation of the factory kit,
clarifying some of the detaile on which the supplied instructions are
ambiguous. If you plan to tow a trailer heavy enough to require brakes,
additional wiring is still needed -- see the RRIII Trailer Brake Control Wiring page.
Factory Wiring Harness Details
The NAS factory trailer wiring package (see photo at right courtesy of Atlantic
British, which is the cheapest source I found and has it for $189)
for 2003-05 model years is part number YWJ500012. (The corresponding
part for 2006 & up models is YWJ500480). It consists of the
following:
A wire harness with a 7 pin Euro trailer connector at one end and various terminals and multiplugs at the other;
A Ford-branded adapter that translates the Euro plug into the North American spec 7 pin connector;
A trailer ECU that installs in the rear fusebox areand controls the various signals to the trailer;
A relay that needs to be plugged into the rear fusebox;
Miscellaneous fixings.
An alternative part number is YWJ500012K ($199 at Atlantic
British) which includes an adapter for converting the round 7-pin
receptacle to the flat 4-pin plug commonly used for light utility
trailers. They can also supply the adapter separately, as part number
VSA500020ABP, for $17.95.
The harness comes with a fairly good instruction pamphlet, but due to
its exclusive use of cartoon pictures with no words (in an effort to
make it international) there are some points which are not so clear.
The description below is based on my own experience installing the kit,
which along with the use of real photos instead of cartoons might
clarify some of these points.

Kit for 2006 and up models: The wiring kit for the Jag-engined 2006
& up Range Rover is almost identical but not quite; it goes under a
separate part number YWJ500012. It costs about $240. The photo at right
shows this kit (couresy of Atlantic
British). The details that follow show the procedure on my 2004
model, but the installation of the later model kit should be very
similar.
Removing the Loadspace Trim Panels
The trailer harness enters the loadspace through a pre-cut hole in the
bodywork, runs along the rear of the spare tire compartment, and makes
various connections to the rear fusebox panel, located behind te right
rear loadspace trim panels. It is easiest to start by removing all the
necessary panels for access. First, the floor panel covering the spare
tire is lifted to its fully up position, and can then be easily lifted
out. Similarly, the panel covering the storage compartment under the
right rear of the loadspace can be hinged up and lifted out, then the
vertical panel immediately to its right can be pulled out by pulling on
the black plastic handle at its top (photo below left). The molded
black plastic liner of the previously mentioned storage compartment can
now be lifted out vertically.
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Lift tab up (bottom arrow) to
remove lower panel covering storage compartment. |
Closeup of one plastic load
retainer. |
Top & middle arrows show locations of removed plastic load retainers (closeup at right). Lower arrow shows location of removed steel tie-down. Rubber seal is pulled away from lower tailgate to ease panel removal. |
Next, the carpeted trim piece lining the right rear of the loadspace
against the tailgate is removed (photo above right). This entails
unscrewing the right rear chromed loadspace tie-down with an Allen
wrench, and removing the two plastic load retainers located on the
panel by twisting them 90 degrees counterclockwise and pulling them
out. Pulling off the rubber seal around the right section of the
tailgate also helps in getting this panel out.
At this point it is convenient to remove the spare tire -- if you are
fortunate enough not to have done this before it is a most ingenious
process. Unscrew its center fastener, close the lower tailgate, and
hook into its top the plastic handle (atttached to the webbed nylon
ribbons that pass underneath the tire). Lower the tailgate and "Presto"
-- the tire is magically levitated up from its resting place. Stick the
supplied plastic brace in the tailgate latch to hold it in place, and
you can effortlessly slide the tire out.
Finally it is necessary to remove the entire molded plastic molding
that supports the tool kit and serves as a mount for the right lower
storage compartment liner. The
front section of this molding is underneath the carpeted vertical
loadspace trim panel immediately forward of it, so to get it out you
have to pry out the plastic stud that holds the bottom of that panel
down to the floor (see photo below left), and remove the plastic load
retainer on the rear
vertical edge of the panel (same as above -- just twist 90 degrees and
pull out). This loosens the trim panel enough to get the plastic floor
molding out with a bit of difficulty, after undoing its fastenings. The
three recessed plastic nuts holding it to the floor are fairly obvious,
but it is not clear from the instructions that there are also two
plastic clips holding its outer edge to the lower bodywork. These are
released by pulling vigorously up on the outer edge of the
modling (photo below left). Now you can get this molding out of the way
with a bit of jiggling.
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Removing the black plastic molding. Black arrow shows location of removed plastic stud; immediately above it is location of another removed plastic load retainer. The three large diameter holes running diagonally across the middle of the picture are the locations of the recessed plastic nuts retaining the molding. The two white arrows indicate required upward pull on the molding's outer edge to release two hidden plastic clips. |
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You now have all the access you need to install the wiring harness.
Routing and Securing the Wiring Harness
Here is a point on which I found the instructions a bit vague -- get
underneath the rear of your vehicle and peer up in front of the bumper.
You will see a rectangular rubber bung sealing a hole in the bodywork,
about 18 inches to the left of the hitch receiver (photo below left).
Pull off the rubber seal and poke the trailer wiring harness
through it into the spare wheel well so the trailer plug ends up
outside the hole. The replacement rubber seal that surrounds the
harness can be re-inserted into the rectangular hole.
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Looking up and to left under the
rear bumper, white arrow points to rectangular hole in body (covered by
rubber seal) through which harness is fed. |
Harness threaded through the
rectangular hole, with new rubber bung surrounding it. |
From inside the spare tire compartment, you can now route the harness's
main bundle of wires to the right against its rear wall, in the
direction of the rear fusebox (photo above right). The two loose
white wires with ring lugs on their ends are grounded to the body a bit
to the left of the entry point (see photo below left).
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Picture taken from inside the loadspace looking aft. Rigthmost upper arrow shows harness entry point; other upper arrows show its routing across rear of tire compartment to right of vehicle (left of picture). Lower arrow shows terminal where harness's two white wires are grounded. |
Continuing the routing of the
harness across the rear of the vehicle to the space occupied by the
rear fusebox. Arrow shows point where the harness wrapping protects it
from sharp metal on the bodywork. Note beyond that the harness is
routed upwards alongside the thick existing harness. |
Running the main harness bundle across
the back of the compartment, there is one plastic clip that secures it
in place, but otherwise it fairly naturally falls into place. Where it
crosses into the right rear loadspace/fusebox area (arrow in photo
below), there is a metal edge sticking up, but the wire bundle is
protected at this point by a thick cloth wrapping. From
this point the harness is run vertically against the existing wire
bundle going up into the rear fusebox compartment.
Connections to Rear Fusebox
The supplied trailer ECU has to be mounted to the rear fusebox as shown
in the pictures below. The white connector needs to be moved out of the
way to access the fastenings for the ECU; the instructions do not tell
you how to do this so I ended up skinning my knuckles. The photos below
show how it is attached and how to dismount it without exerting brute
force like I did.
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Top Left: Rear fusebox. Note
white connector (arrow) |
After mounting the ECU, the two multiplugs at the end of the harness
can be connected -- the black one to the top of the ECU and the white
one to the white plug mentioned above, which can then be restored to
its mounted position (photo below left). Then, you can insert the new
relay supplied in the kit into the empty spot at top left of the relay
cluster (photo below right), and replace Fuse 1 with a 30 amp fuse (not
supplied).
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Black multiplug connected to top
of trailer ECU, and white multiplug connected to the white connector
immediately to its right. |
Top arrow shows connector that
has to be removed for next step, to insert red wire into it. |
In the photo above left, note the blue wire dangling in the breeze at
top right; this is simply referre to in the instructions as "unused".
It actually comes from the
brake terminal on the trailer plug, but no provision is made for its
termination. It would be an easy matter for Land Rover to provide for
it to be connected to the main wiring harness and emerge in the
vicinity of the driver's feet so an aftermarket trailer brake
controller could be simply plugged in like it can be for Chevy, Ford,
Dodge, Toyota and Nissan trucks and SUVs. As thing stand, however, you
have to wire up a brake controller to this blue wire manually -- this
problem is dealt with in detail on the RRIII
Trailer Brake Control Wiring page.
The next step is to add the red wire from the trailer harness to the
white connector immediately above the relay cluster. First remove the
connector (squeeze its top and bottom to release its catch). The
wire has a metal tab on the end to clip into the plug -- the photo
below left shows the correct hole into which to insert it (not clear in
the instructions). I found it required massive force with a pair of
pliers to insert the wire before it clips into place -- don't be afraid
to push it hard!
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Red wire being inserted into 2nd
hole from left in top row of white connector. I spread the tabs
inside the plastic connector a bit with a small screwdriver to try and
ease the way, but it still needed considerable force. |
Harness wiring completed, with
diagonal red wire at center affixed to connector above relay cluster. |
We are now done with the wiring, unless you are towing a trailer that
has brakes -- in this case you need to run the "unused" blue wire
referred to above forward to the vcicinity of the driver's feet. This
and other details of brake controller installation are dealt with
separately on the RRIII Trailer Brake
Control Wiring page.
Reassembly
The panels and moldings you removed for access now have to be
reinstalled. This is straightforward except for a couple of items dealt
with in the photos below.
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When replacing the plastic
molding that holds the tools etc on the right side of the loadspace
floor, the plastic nuts are hard to get back on to their deeply
recessed bolts. A magnetic socket is no use, but I found a pair of very
long nosed pliers helped i getting the nuts into position and the
threads started. |
The two-part plastic studs that
hold the carpeted trim pieces in place come out easily enough, but
putting them back in is another matter. I found that extending them to
their full length allowed me to squeeze the ends together enough to get
them back into their holes, after which a hard push or a bash with a
hammer seated them back into place. |
If you are just towing a light utility trailer without brakes,
your wiring job is complete and you can use the 7-pin to 4-pin adapter
supplied in the kit. If you are towing something heavier, trailer
brakes are needed. See the RRIII Trailer
Brake Control Wiring page.
Parts Sources
Atlantic
British -- has low prices on two versions of the factory wiring kit
with and
without the 4-pin adapter. They also sell the adapter separately.
The
Rover Connection -- low prices on all genuine parts including the
trailer wiring kit.
More Information
Setting up a RR III for Towing
RRIII Trailer Brake Control Wiring page
Dash
Trim Panel Removal Page (RR III/L322).
Return to Range Rover Outfitting
If you have corrections, comments or suggestions, email us.
Page revised February 9, 2012