Okay, so here's the deal. The PO (Typical PO) half-*** installed a Wal-Mart brand trailer wiring system. In turn, I think, my left bottom bumper turn signal does not flash, but the right side does flash. Of course, the entire left turn signal flashes rapidly, it thinks the bulb is blown I guess. Here's the weird part, when I do hook up a trailer, the turn signal flashes normal speed (Still no bumper signal though.) Does anybody have any ideas as to why the turn signal only flashes normal with a trailer hooked up? The rapid flashing annoys the crap out of me, and it seems like a simple fix, but I am dreadful with wiring. Any help is appreciated. Thanks

 

Turn signals 101-the flash speed is dependent on the electrical load on the system, lighten the load (burnt out bulb) and it flashes fast.
Add more load and it slows down.
So with a burnt out bulb adding a trailer adds load so the flashing slows back down.
Most likely you need one of these or maybe even both.
Bulb Holder XBP100180 Harness Repair Kit - RoverParts.com - Land Rover Parts & Accessories
And
Bulb Holder Single Filament | Land Rover Electrical Parts, Batteries, Relays, Lamps & More
Remove the non working bulb holder and bulb, check to make sure the holder is in good shape.
Turn on your hazards and swap the holders, the good for the bad, does the bulb now work?
Also check the connections on the wire harness, they get corroded and then the turn signal will not work.
I have had to replace both of mine with the repair kit.
Also buy the bulb holder in pairs and keep the extra in your garage.

 

Once again Spike, you're the man. I'll get under the Rover tomorrow and have a look

 

Those bumper turn signal bulb holders like to corrode away into nothingness because they get all the water from the rear wheels and splashing from the road as well as the road salt in the winter.
I'm going to make and install mud flaps this summer and see if that helps.