Some drivers never use indicators.. But most drivers definitely appreciate and use indicators in old-fashioned car-to-car communication. Real technical faults in the indicator system are quite rare these days. The most common ones are broken lamps. In order for the driver to notice, the indicator light on the dashboard flashes faster. This signal confuses some people because fortunately it’s rare.
But this is exactly what it says in the rule book. A faulty indicator lamp needs to be signaled to the driver. The fact that this happens through the indicator flashing faster is a remainder from times when the yellow lights were still controlled by a thermal flasher unit. In this primitive technology, which today can only be found in vintage cars at most, the flashing frequency is basically increased automatically. Today, special flasher relays or central electronics make the indicator lamps flash 90 times per mi-nute – or faster if a lamp breaks. This is now achieved through current detection. If too little current is flowing because the lamp won’t draw any, the flasher unit or control device will switch to a higher flashing frequency. For the sake of accuracy it’s worth mentioning that only the main indicator lamps are monitored in this fashion. Failure of the small side indicators won’t necessarily trigger a fault message.
Trailer indicators usually have their own control lamp. In some cars it flashes briefly when the indicator is used, even if there is no trailer. That may be confusing but is pretty standard.
It’s obvious what you need to do if a lamp starts flashing too quickly: replace it. In some cars this can be quite fiddly, but there are longlife lamps so you won’t have to bother too often. Osram sells them under the name Ultra Life. They only cost a bit more but last between twice and three times longer.