Automotive Flasher Question

I don't follow your comments. I think my car uses a single turn signal flasher, and the right or left is accomplished by the downstream contacts manually operated by the turn signal lever on the steering column. And what is a "4 way flash"?

My thought was I have noticed some recent autos where, when the left (or right) turn signal is activated, the front and rear turn signal (and dashboard) lights flash on, while the front quarter and rear quarter side lights (and maybe light on the side mirror) are off, and then when the front and rear lights cycle off, the side quarter lights flash on, etc. This would seem to maybe have an advantage of reducing the peak current that has to be handled by the switch contacts as compared to a design where all six left turn bulbs were operated simultaneously. Do cars with this alternating flash design use a SPDT flasher, and if so is this the 5-pin device at the parts store, or do they use a more traditional 2, 3, or 4 pin SPST flasher in some more elaborate wiring scheme? Gary Q

Here is an idea that may work. I worked as an auto electrician most of my life, but primarily know the old tech.

One bulb will be light from the turn signal flasher when it's conducting and the other bulb will light when the flasher is not conducting. This is possible if a relay coil for a double pole double throw relay can be energized from the flasher to open the circuit of the second bulb. The second bulb is powered from the same power source and through the load contact of a relay.

When the flasher is not conducting (off) the relay coil is not getting power so the normally closed contacts will now light the other bulb instead.

Use a lamp and bulb socket such as in auto back up lights. Bulb part number

1004 if I remember correctly. They are single filament with a single contact. They put out about the same candle power as a brake/turn light. The bulb holder base is the ground side.

Use a #536 flasher as it's flash rate is not dependant on current draw of the bulbs. This unit has two terminals.

Use a single pole double throw relay rated for 12 volt coil voltage. Use a filtered 12 volt DC power supply and I think Radio Shack sells them also.

Connect the ground from the power supply to both lamp bases and one terminal of the relay coil.

Connect the power supply positive to the battery side of the #536 flasher and a parallel wire to the center terminal of the relay. In other words, power up one the contacts of the relay that would distribute power to either contact whither the relay coil in on or off.

From the other contact of the flasher (load side) run a wire to only one bulb positive. The other bulb positive is now wired to the relay contact that is normally closed.

A professional would advise placing a fuse in the circuit small enough so a short won't fry the wires or power supply

You could get a project book and build an astable multivibrator on perf board. I am not at all interested in electronics and avoid doing electronic projects like the plague. This one, however, is easy and simple such that even I can do it with help from the book. It is cheap and can be duplicated again and again for very low cost. The trigger can be supplied in a variety of ways and the flash rate is adjustable. True, it is not plug-N-play, but it's not hard and once you've done it once, you can do it again in a small fraction of the time. The whole thing with the automobile flasher is a bigger PITA because you're modifying someone else's design to operate outside it's intended parameters. Sometimes it's easier to go from scratch.

I can't answer your questions because I am not familiar with the new autos turnsignal systems.

My feeling about the turn signal flasher is that for a left turn, you energize one pole of the unit, and for a right turn, you energize a different pole. So they would not be usable the way you want. If the technology has changed, then what you describe below should work the way you want.

Sorry about the c>> I don't know about the pinouts, but remember that there is a left

The way you mentioned of controlling a sp/dt relay coil with a auto flasher unit will also do the job. That all is dependant on the relay coil drawing enough amps to trip the flasher. I correct myself on the part number of that variable load flasher as a #555 rather that a #535

Here is a flasher circuit that is designed for 12 volt automobile lamps. Refer to the fourth circuit on the page.

Rob.