Resistors are only a couple of dollars.

 

Yes, but they must be installed, and probably must be installed somewhere out of the weather and where the heat they generate won't be a problem. Also, apparently relays are required as well and it sounds like it turns into quite a bit of messing around. That extension cable with the in-line circuitry looks like perhaps the simplest and most versatile, but I doubt it will hold up to a lot of miles of bad weather.

I have a specific question: On which circuits is the Rover looking for incandescent bulbs? Is it the tail light or brake/turn circuits? Or all 3?

 

Indicator circuit only but you also need relays to stop the pulsing, i have mine tucked into the LH storage compartment with a switch to turn on and off and its hard wired.

 

FYI a good technical thread on this problem https://www.rangerovers.net/threads/...mputer.189834/

 

I have no knowledge to ad but I wanted to say my 2005 V8 LR3 has the EXACT same issue. bought a 7 pin plug in kit from AB and my trailer tail lights flash even when car is off, my backup sound doesn't work anymore, my parking button on upper dash is flashing and when trailer is plugged in and indicators are on the little trailer symbol doesn't show up on dash. I'm also getting an intermittent parking symbol flashing on my dash for 1 minute after turning car off. Until now I didn't think these things were all related but.....
Hopefully this details an knowledgeable thread will help me out. Just wanted ot let you know your not alone.

 

I put resistors in-line on the left and right indicator wires and nothing changed at all. I guess i'll try relays next.

I have:
no trailer icon
backup sensors still active
brake lights still pulse (a little faster than once per second)