Blinker Delay

[4th effie n counting]

Just curious, when did they start making signals that didn't blink because a bulb was out?
I know i've had vehicles where this was the main cause of no blinky. No blink i check bulb. I doubt this is the case for a '67 tho.

[seattle67]

Actually, its the older, thermal flashers that don't blink when the lamp is burnt out. There is a bi-metallic "arm" on the contact in the flasher, when you turn on your blinker switch, current flows through this bi-metallic contact and then through your blinker lamp making it light up. This current causes heat and because the "arm" on the flasher contact is made up of one type of metal on one side, and another type of metal on the other, the contact arm bends when heated. (kind of like those furry snake toys that arch their back as you pet them)
It eventually will bend enough that the contact opens, when this happens the blinker lamp goes off and there is no longer any current flow. No current, no heat, so the bi-metallic contact arm cools off, goes back to its original shape and the contact closes, starting the whole process over again. (Modern science, it boggles the mind!)

That is why thermal flashers don't work with LED lamps, LED's don't pull enough current to heat up the bi-metallic contact in the flasher, so they don't flash. Its the same if your blinker lamp is burnt out, burnt lamp = no current flow, no current flow = no heat, no heat = no blinky!

The newer flashers use electronics to just tell the flasher to turn on and off, they don't rely on heat. So they will work on LED lamps and continue to flash even if your lamp is burnt out.

[fordman]

thats interesting. i knew the flasher cans had a kind of points contact in them but i didnt thinkit was heat activated. i thought it was some sort of relay deal.