I need to have a look and see what type of bulb it is. I think it is a bayonet single contact non offset but I could be wrong. It may not work because the stupid computer might decide that as the current has changed the bulb must have blown. Then I think the flashers go on rapid time to warn you.
There are load resistors you can add to overcome this. AsI say, I need to get my screwdriver out and have a look.
This sounds way too advanced for me, and would be a classic way for Ford to back out of warranty work. I will leave well alone, and as said before supplement the reversing light with the flashers and rear fog.
John Hi, A headlamp bulb would be illegal. Maximum wattage for reverse lamps is 21 watts. based on standard bulbs. LEDs are a different story. They have an equivalency rating. E.G 2 watt led =6 watt bulb
Only argument is that many if not most cars have 2 reversing lights; 2 x 21 w. = 42 w. I know a 55 w. bulb is illegal, but most of your reversing is on your own drive or in a car park; just make sure there are no police around.
Last time I looked at bulbs in Halfords I noticed the maximum output for headlights were 55 w. I see that they now have some 60 w. types. What are the B Max specifications; are they H rated ??