I tow my 2019 Troll 540 with either a 2016 435d BMW or with a 2020 V60. The BMW is fitted incandescent bulbs, the V60 has LEDs.

Last year I did 1,500 miles in the BMW across Europe and back without any issues. Last week I went on a round-trip of 250 miles and started getting multiple intermittent bulb failure messages for each of the "trailer lights" on the van. The messages came and went, apparently at random. I have never seen the issue with the V60; neither last year nor this year.

So I stopped the car to check and found that some of the van lights were actually not working. I then switched-off the ignition, disconnected and reconnected the electrical connection between the car and the van and found the lights worked without issue for a short while (10 mins) before the random bulb-failure messages started appearing again, albeit with a lower frequency.

Since getting home I have thoroughly cleaned the car's connector socket and carried out lighting tests on the driveway. All worked and no alarms have appeared...yet!

I have read that cars using the CANBUS system for management and which are equipped with incandescent bulbs (like the BMW) can throw out bulb failure alarms if connected to a trailer/van with LED bulbs. This is reportedly because when the CANBUS system performs a routine bulb check, it is looking for an incandescent bulb electrical load which is significantly higher than the load generated by an LED bulb. Hence the system thinks it has a failed bulb when it tests an LED circuit..

I know that it is possible to buy adapters to address the issue but they are costly and some of the feedback suggests that they often don't work. (Carpoint 0440140 Canbus LED Adaptor 13-Pin on Amazon £58)

My reason for posting is to ask:
1) Has anyone else seen the bulb failure messages issue and resolved it - especially if towing with a BMW?
2) Can anyone suggest a reason why the bulb failure messages have only just started appearing? (this is the 3rd year of towing with the BMW)
3) Has anyone ever bought one of the LED trailer light adapters and did it work?

Cheers

could put led bulbs in eriba, although would still spark the warning

under the floor, the older eribas there is a box with wires for lights in, check to see if connections gone green causing a higher resistance, clean there is a spray minds gone blank on name.

my lower front lights the connections needed cleaning behind the capless 501 bulbs.

the car brain remembers faults see if can get them cleared,