Signal Flasher Issue - 1935 Ford Pos Ground ?

[ScubaChief60]

Hello all... I looked at many threads and not sure I have my answer. I kept my 1935 Ford as a 6VDC Pos Ground. I am using a 6VDC to 12VDC step up device to power 12VDC headlights and the front and rear signal and park lights. They all work great. My issue is that the flasher is not working. Use of the 6VDC 535 Flasher has the LED signals all lighting up... but no flashing. I have a 12VDC LED type flasher unit ( EF-33RL / 3P 12V )with a ground wire out it's top and I have been unsuccessful even getting the lights to light up with this EF-33RL unit. Do I need some resistor etc. to increase the load on the setup for the flasher to function? Any advice appreciated. I tested the LED Flasher Unit and ground it... and nothing. I have seen threads about use of resistors at each of the four lights... Figured I run it past all of you guys and gals first. Thanks!

[BlueSpark]

Hi- Yeah, the old type of flashers use the lamp current to heat a bimetal strip. When the strip gets warm it bends, opening the circuit. LEDS dont pull enough current to heat it up enough. I believe the flash speed is dependent on the current. (If anyone disagrees lets hear it! Its been a while.) The idea of adding resistors is to increase the current so it will work. They will just dissipate the power as heat- I wouldnt mess with them unless you are a purist. I looked at the EF-33RL info on the manufacturers site but they dont give any schematic information. Did you get any information with it? I think I know what the connections are but not 100% sure, see if this makes sense. P is +12V. L is Load (lamps), X is no connect. But since these use an electronic oscillator to drive the contacts they need a common, hence the ground wire. I assume your 12V converter is isolated and the negative output goes to ground, so if you connect the P to +12V it should operate, even without a load. If it was ever connected in reverse the oscillator may not have survived (not a great design but not uncommon). Did you connect the P terminal and the ground wire to a 12V supply on the bench?

[ScubaChief60]

I appreciate the reply. No information came with the EF-33RL. Also... yes the 12VDC is isolated and the signal switch is also isolated from the 6VDC Positive ground too. I will bench test it.... have not done that. I appreciate it!

[petehoovie]

Part # EF33RL Description 12V 0.10-20A 3PIN LED FLASHER Type Variable Load LED/Incandescent Compatible Flasher Typical Load SAE No. 1156 2.10 Amps at 12.8 Volts SAE No. 1895 0.27 Amps at 14 Volts 1 to 12 Lamps or 2 LED Lamps In Any Combination at 25 Amps Total Specifications FMVSS108, SAE J590b J945 & J1690 Terminals3Rated Load Range0.1A to 25A Self-Adjusting to Lamp Draw Flash Rate60 to 120 Flash Per Minute Style Round Plastic Rated Voltage 11 to 15 Volts D.C. Lamps TurnN/APilot Circuit Yes Wattage 300W Life Hours 600 Hours Drawing D
Details Click on this PDF for wiring schematic > EF33RL.pdf

[BlueSpark]

Oh OK. I was wrong! I missed the link to the drawing. X goes to +12V, L to the load, P is for a dash light, probably the opposite contact of the load meaning it will be ON when the flashers are off, and vice versa. So I hope you havent connected it the way I said... With X on +12V and the wire to common it should click away, unless its the silent type but I doubt it is.

[ScubaChief60]

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Hey I appreciate the information. I have not tried anything yet... most likely will on Saturday. Thanks both of you. I'll loop back after I get it going with what I learned and it may help others down the road.