Emergency Flashers

I recently followed a driver who had his emergency flashers on. I noticed his brake lights didn’t seem to be working. I’ve also had the aggravation (on several occasions) of following cars in heavy rain that activate their flashers and continue to drive. Do the flashers override the brake lights or possibly use the same bulbs? If they do, it’s really dangerous to be driving with the flashers on. The drivers behind you would have no idea when you apply the brakes.

I wont say there are no cars with flashers that use the brake light bulbs, but all the ones I have seen use the turn signal bulbs, or the running light bulbs, not the brake light bulbs. Standard transmission cars however can slow a great deal without use of the brakes at all and this can be a problem for those who are used to automatics. Perhaps the reason this particular driver was using his flashers was that his brakes lights had failed and he knew it?

On my car the 4 way flasher use the amber turn signal lamps. The brakes are not connected. I don’t know about yours.

I too have only seen ones that use the turn signals. At least I think I have. I guess with the tens of thousands of different models and model years on the road there must be some that use the brake lights. Unless, of course, D.O.T. mandates otherwise.

Actually, if his brake lights aren’t working he’s probably safer to have turned the flashers on than nothing. At least it alerted you that there was a hazard.

Thanks to all for your helpful responses. I did check my own cars and its the amber lights that flash. So my guess is this fellow’s old minivan was broken or it was so old that it pre-dated DOT rules.


I had a 73 mercury that used the same bulbs for the hazard lights and the brake lights. If you had the hazards on and pressed the brake pedal, then all lights (brake and front turn signals) came on and stayed on until you released the brakes. If the hazards were off, then everything worked correctly. It’s easy to assume that some cars might operate the way that the OP describes. I assume that most if not all would be fairly old cars.

I once lived in a state where it was illegal to drive with your emergency flashers on; they were considered to be for a stopped vehicle only.

Did you try to research this using your own car? If your first thought was to run to the internet, you might want to read the President’s most recent commencement address:


As for not being able to distinguish between brake lights and turn signals, well, I am just disappointed. So disappointed.

In the designers, of course.

There are a couple of scenarios to this. First, I don’t think anyone has pointed out that there are both vehicles with amber turn signals in the rear and those that have red combination turn/brake lamps that take care of both functions. If the driver had a vehicle with only the red turn/brake lamps it is likely that the brake signal does not override the hazards. The other scenarios are that his lamps were broken etc as others have suggested.


if you are driving, especially in rain, following a car with the flashers on…you have to drop slow down and drive accordingly…they are indicating that they are driving slower…

Every car I have owned in recent decades uses a type 1157 brake/flasher bulb. These bulbs have two filaments in one package. One filament is used for the turn signals and emergency flashers and the other for the brake lights. You can have neither filament lit (normal), just the brake filament lit, just the flasher filament lit, or both lit. The last occurs when you brake while the flashers or turn signals are working. It’s brighter than either filament lit by itself. See http://autorepair.about.com/od/electricalrelateddiyjobs/l/aa010502b.htm

That is a negative. The two-filament bulbs serve two functions. The smaller filament works when the parking/head lights are turned on…a dimmer version of the larger filament, which is brighter for turn signal/brake light function.

Wrong. Brian is correct.