Leaving Wolf Performance last night my reversing light wasn't working. A dig about today showed that water & corrosion in the bayonet fitting were to blame.
The photo shows the inside which I cleaned up.


The wires enter the fitting via a rubber boot. . The boot can rotate on the bayonet fitting meaning the boot can point upwards & mine was. This acts like a funnel feeding water in
I fitted it back facing downwards & fitted vaseline to the o ring seal on the fitting. The photo is of the fog light which I also treated to vaseline.

John, on my 2002 car both the rear fog and reversing lights have screw on lenses. The whole lens screws on, not fixed by two screws as is the norm. When looking for a fog light fix the bulb holders were starting to show slight corrosion as discolouration. I cleaned them Plus used vaseline on the threads to add some extra sealing. I sprayed Dinitrol on the backs inside the panel. The foglight problem was caused by the control unit behind the dash. That is another epic story! DIY repair dueto big struggles getting a replacement.

Yes I went through 2 PCBs on my 2006 Roadster.

That's a yucky mess John. I recently bought a tin of silicon dielectric grease which I smear on bullbs and connectors now. Such may be useful in repair.

When I recently did the twin reverse/fog conversion I had to change the bulb holders. The soldered joints to original plug leads made close to the holder, were insulated with shrink sleeving then bound with insulating tape up to and over the right angle rubber cover. Hopefully no similar issues.

The earth was a push on connector the power is soldered but heat shrinked. There was no insulating tape, I guess that is MMCs solution to seal the end of the boot which is open. I used a tie wrap & then sprayed the installed unit in damp start.

Sorry John, I didn't make it clear. I added the insulating tape to cover connections to new bulb holders outside of boot. Otherwise previously as yours, with the right angle boots set horizontal at sheathed cable exit. Within boot there were narrow spade connectors for both polarities on bulb holder. New bulb holders had short flying leads hence need for soldered joints.

ETA: From your description I suspect a PO had earlier issues with reversing light leading to positive spade connection being re-made as soldered joint. Worse though was leaving the rubber boot exit facing upwards

Dear John,

in my 2018 plus4 both rear lights (fog and reverse) look like a fish can live in. Made in Germany, HELLA.

With a look at the construction it would be allways a wet thing. My idea is to change over to the classic LUCAS lights with two drainholes downside.

René trust in british engineering

Water in the lights.....
My rears have been ok but the front indicators had water inside. I used two fixes.
Drain hole in the bottom and improved the seal where the wires came through the wing. Under the wing is a really tough environment due to water off the tyres. Also the bullet connectors for wiring are the wrong type in my opinion. I changed mine after a poor front light connection due to them corroding. It was impossible to pull the bullets out. I cut the wires and rejoined with connectors and heat shrink.

I have used the drain hole in the pas on one of my old cars. for the front indicator.

Yes, that‘s the idea behind my thinking.

The front indicators are easy to service (and cheap) the new „Hella style“ are a little more difficult, especially if you haven‘t got a sparewheel.

Rene