K12 reversing light head scratcher

Hi. New member here.

I've just inherited my mum's 53 plate K12 1.2S. (Only 40k miles! )
The reversing light isn't working. I've trawled the forum already and tried all the advice offered here and I just can't figure it out.
I've metered the lamp holder, and it's showing 12v across the terminals when in reverse, and 0v when not in reverse, which I think rules out the gearbox switch and the fuse, but when I pop a bulb in it still doesn't work. (I've tried new bulbs and even metered them for continuity and they're fine)
Any ideas?
I have a 2004 and had this problem on my front indicator.
My solution:
Get a small file, or sand paper, and sand down the contacts; just enough so that they are shiny - and being careful not to bend them as that would make it difficulty to get the bulb back in.
Put in new bulb and the job should done.

Hope this works for you.
I have the same problem. MY mechanic temporarily fixed up but then it packed up again. Have taken to reversing with hazards on lol


Club Member
Radio Code Guru
An update on fixing this all too common problem on the K12.....
As mentioned in an earlier thread I had this exact problem shortly after getting my K12 a couple of years ago. I determined that it was a high resistance connection between the bulb and the power feed as I had 12v on the connection on the back of the lamp unit but the bulb would not illuminate.
'Fiddling' (scraping and bending up) with the centre connection in the lamp base appeared to cure the problem.
However it returned last week and again the bulb was OK and 12 volts was present. On closer inspection I appear to have finally pinpointed the source of the problem.
The +ve feed into the lamp unit is direct, via a single piece of plated steel, from the plug pins to the back of the individual lamp sockets:-

Where the potential high resistance joint occurs is where the copper strip that makes contact with the base connection of the bulb, it just clips onto the plated steel +ve feed, so any looseness/corrosion here gives a high resistance joint, which only becomes apparent when an electrical load (21W lamp filament) is connected to it....

Cleaned both surfaces and soldered the two parts together.........

Note you need a very hot high wattage iron with a small bit to achieve a decent soldered joint here....
High resistance connection eliminated:cool: