Are they LED indicators or with filament bulbs?

You need to be careful with aftermarket filament types as they are often supplied with 21W bulbs. The XT indicator relay needs 10W bulbs; the relay can cope with max 10W x 4 = 40W (3.3A) which will allow 2x 21W bulbs to flash because that's roughly the same demand as in hazard mode (4x 10W). However, as soon as you hit the hazard button you've 4 x 21W = 84W (7A) and is too much for the relay (and the fuse when you add the other loads of sidelights etc).

If they're LED they may well do funny things because of the opposite reason - they'll draw too little current (unless resistors are added or a new electronic relay is fitted). Usually this just means they flash fast, but other problems can manifest themselves too.

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