Has anyone ever stopped at a light or sign and looked at the vehical turning in front of you? Have you ever looked down at your signal light flashing and compared it with theirs. Have you ever seen a blinker that flashes at exactly the same rate as yours? me neither. Why? Would identical Models and makes of specific vehicals flash at the same rate?
I think that two cars of the same model would blink at the same rate. It would just be very unlikely that they would blink simultaniously.
Since it is a cycle that you can compare with your blinker, even very small changes are noticeable after a minute, so it makes sense that they don’t stay perfectly synched. These lights aren’t timepieces after all.
This is just an opinion, but I suspect that minor differences in battery voltage, wire condition, and perhaps even the conditions of the bulbs themselves would have enough effect to make noticeable variations, even on identical cars. Ever notice that if someone has a broken turn signal, that the other light blinks much faster? Less power needed, therefore the capacitors charge and discharge faster. At least that’s what it seems like to me…
With cars of different makes, since there is no standard requiring a specific speed, the wiring is probably just done in the way that is most convenient for the car maker. Different wiring, different rates.
It seems to me that the left and right blinkers blink at different speeds. I just love it when someone blinks left and turns right. Makes it more interesting to drive.
If someone’s left and right turn signals blink at different rates, there’s something wrong with the blinker control. They need to have it replaced. Take it from someone who’s been there.
Kells, we’re more alike that I imagined, and that scares the bloody living hell out of me. I’ve watched that all the time - generally two different cars, and just watched the pattern of blinks go in and out of phase with each other.
Then it happened.
I was crossing the campus at Georgetown one night and noticed two cars parked, one in front of the other, both with their hazard blinkers on. When I noticed them, they were in perfect synch.
And they stayed that way.
For the three minutes I watched them.
I literally couldn’t tear myself away! Those damn things had to go out of synch eventually and they WOULDN’T! Two different makes of cars and they were keeping perfect rhythm with their blinkers.
It happens. God knows how often it does, but it happens.
Cave Diem! Carpe Canem!
Blinkers are not timed by an in-dash computer or anything like that. They work by a thermostatic trick; when power is on, the gadget gets hot; when it gets hot, it cuts the power; then it gets cool, and brings back power again.
You might as well expect raindrops to work in sync.
John W. Kennedy
“Compact is becoming contract; man only earns and pays.”
– Charles Williams
Like Xmas tree lights! 
That makes perfect sense.
The voltage going to the blinker unit also affects the blink rate, which is why some cars blink much slower when sitting at a stop light idling than they do when they’re moving. If this suddenly starts happening to you, you should probably check out your electrical system and make sure everything’s working properly.
A couple of months ago the alternator on my car quit working. I managed to make it home, but on the last turn when I used the signal it never blinked at all… just sort of came on and stayed on while the headlights dimmed. The flasher unit wasn’t getting enough juice to trigger the off cycle.