'Fast' indicators - sometimes

[gjm 3258]

2001 E46 318i.

Sometimes - not every time - when using the indicators (very un-BMW like ) they will flash fast a few times, then flash at normal rate. Sometimes they'll flash fast and not slow before cancelling. Sometimes they will flash at the correct rate. I don't think they have flashed at normal rate, and then started to flash fast but it's possible. 

This happens in both directions - left and right. No towbar fitted or towing electrics.

Doesn't appear to be a pattern as to when it does(n't) happen. Might be a hot day, a wet day, early morning, when having been driven briefly or for a while.

To be honest it's kinda funky! Fast flash to attract attention, then a slower flash. I quite like it, but it is wrong.

What's the most likely cause? Dirty relay contacts?

[Eagle 1662]

Id be checking the rear light bulb holders and contacts then the wiring if needed. Bad grounding usually the issue.

[gjm 3258]

23 minutes ago, Eagle said:

Id be checking the rear light bulb holders and contacts then the wiring if needed. Bad grounding usually the issue.

I've not looked - is there likely a single ground commoned for both sides?

[Eagle 1662]

Usually have a collector which mounts them together somewhere on the body. The tailight end plug\connector terminals are where the problems are of the time in my experience. Easy to check.

[gjm 3258]

33 minutes ago, Eagle said:

Usually have a collector which mounts them together somewhere on the body. The tailight end plug\connector terminals are where the problems are of the time in my experience. Easy to check.

Narrows my search.

Thanks.