How does the flasher unit work

[BN6_2197]

Gents,

I have a good understanding how the flasher relay works. But I have no idea about the flasher unit.

I expect 12 Volt at L and B if the direction switch is in neutral state and 0 Volt at P. Is that right?

If the direction switch is operated to left or right, I still expect 12 Volt at L and B but alternating 0 V and 12 V at P. Correct? But how is the alternating current generted depending on the state of the direction switch.

I am asking since I observe that 12 V is at P even if the direction indicator is in neutral state.

Volker

 

[John Turney]

Here's the connections:
B = battery
L = lamps, the actual exterior lamps
P = pilot, the dash lamp

I expect 12 Volt at L and B if the direction switch is in neutral state and 0 Volt at P.

That is correct.

If the direction switch is operated to left or right, I still expect 12 Volt at L and B but alternating 0 V and 12 V at P.

When the direction switch is operated left or right, there will still be 12 volts at B, but L and P will alternate between 0 V and 12 V in unison.

Go back to your earlier thread,http://www.britishcarforum.com/bcf/...-of-Flasher-Unit-(warning-lamp-does-not-work) and look at the photo in my post, #9. The L contact and P contact operate together so the external lamps and dash lamp should flash in unison.

Hope that helps.

 

[John Turney]

Perhaps it needs this: https://www.britishcarforum.com/bcf/showthread.php?119939-Finally-found-it

 

[blueskies]

I like John's suggestion. But, if that doesn't help . . . have you tried replacing the flasher unit? They do fail. I recently damaged a nearly new flasher unit while trying to reinsert the dash flasher bulb that had fallen out of place back into its socket in the dash. I inadvertently left the key on, and a brief spark resulted from touching who knows what. The signal lights still worked but the dash indicator no longer flashed. A new flasher unit solved the problem. Works perfectly again.

 

[vette]

Here is my scribbled up pic trying to explain it. I may not have it down perfectly but I hope this helps. Looking at my pic of the inside of the flasher see that the actuating wire is what heats and cools and opens and closes the contacts. L will have voltage on it when the ignition sw is turned on. But L just leads to the #1 terminal on the turnsignal/brake relay which is not connected thru to anything until the trafficator is turned. When the trafficator is turned the the turnsignal/brake relay energizes and connects #1 terminal which is power from the "L" terminal to one of the front and rear turn lamps. This initial current thru the flasher unit from B to L via the actuating wire and the coil will cause the contacts in the flasher unit to close. Then the power goes from the B terminal to the L terminal via the coil but bypasses the actuating wire. This cools the actuating wire and the contacts are pulled open again starting the sequence all over again. When the contacts are closed in the flasher unit the contacts on the right side are also closed and this put power directly to the P terminal which energizes the dashboard indicator light. The P terminal should have no voltage on it until the trafficator is turned which initiates this flasher unit to close its contacts. The dashboard indicator light or lights are grounded differently depending on the year of the Healey. The cars with one dash indicator light the dash bulb is grounded right there on the back of the dashboard. The cars with two dash indicator lamps use an extended ground circuit which runs a wire from the respective dash indicator lamps to its corresponding front turn lamp terminal at the turnsignal/brake relay. As such this grounds the dash lamp thru its respective front turn lamp bulb. As an example the left side dash indicator bulb is grounded by a green/red wire that runs from the bulb to #2 terminal on the turnsignal/brake relay. When this bulb gets energized from "P" it is grounded thru the left front turn lamp bulb. See pics below. Hope this helps.

In the first pic I have written under "P" that this wire goes to the ground side of the dash lamp. The should not say that. This wire is the hot wire to the dash lamp.