I recently towed for the first time with my 2006 LR3 4.4 V8 and had no parking lights on the trailer when I hooked it up. Troubleshot the connector and found no power coming out from the wire for the parking lights. I traced further back to the harness plug in the rear left compartment and still no output for that wire. I have brake lights, turn signals and hazards, but no parking lights. Also the trailer light doesn't illuminate on the instrument cluster. to make it home, I connected the parking light wire from the tail light to the trailer harness to have parking lights so I would be legal and they work, and when I put the turn signal on the trailer light flashes with the turn signal indicator. Where is the trailer light control module at, or what could be the reason I am not getting voltage to the brown (parking lamps) wire output. I have tested all the way up to there the trailer harness plugs in and still no voltage. Thanks to all.

 

I would check the fuses in the Passenger Compartment fuse box.
Fuse# 6 is the TOW Reverse light
Fuse# 8 is the Trailer Pick-up Battery Feed
*Fuse# 14 is the Tow Side Marker Lamps. This is probably the culprit.
Fuse# 22 is the Trailer Pick-up (Ignition Feed)

Check those !!

 

Got it. Fuse 14. After looking closely I saw it was blown on the edge. Completely fo rgot about the fuses behind the glove box. Now if I can only get my defrost to now air.

 

Glad you found it. 80% of the issues i've come across on my LR3 are electrical related. Usually just a bad connection or if under the hood, corrosion related.