Hi all:

I recently converted the taillights and rear turn signals with LED bulbs. Worked great! Then changed the front turn signals with LED. Won’t work! It also caused the rear turn signals to not function also. Instead the all of the left/right/rear/front turn signal lights just lit up without blinking. The green turn signal indicator on the dash did not light up.

After I replaced the front LEDs with the original incandescent bulbs, the front/back turn signals work again in blinking as it should as well as the signal indicator on the dash.

Now, I am figuring that with the regular flasher relay I have, it works because the current load drawn from the front incandescent bulbs was enough to make the relay click on/off.

So I bought a LED-compatible relay. With it installed, nothing worked. Not even lit up at all, whether completely LED or partially incandescent. That new flasher had a ground wire. Perhaps it was just a dud or not compatible for 122S? Would a flasher without ground wiring be better?

Any guys out there with success stories of completely converting their 122S projects into using LEDs all around without any turn signal issues?

If it helps to add more info about my car, it’s ‘67 but has emergency flashers installed from a ‘69 122S. Also converted to use 63-amp alternator.

Thanks in advance for your advice!

-DS

DS;

You understand it right...by only changing one end to LEDs, the incandescents on the other end still drew the (high) current needed to cycle the OE bimetalic Flasher Element. Flasher element in a 122 is a two terminal type. By making all lamps LED, circuit current fell below what FE needs to operate.

Yes, to run LED lamps, an LED compatible FE must be installed, and these typically have a chassis wire needed to run the electronics. It sounds like you did it right, but I seem to recall some variations in the terminal designations of flashers.

Note also that Blinker Indicator in dashboard may not operate, because of the way it is implemented. See also: http://www.sw-em.com/Blinker_Relay_or_Element.htm#Two_Terminal_%20Blinker_Element_%20in_122

Please post a follow up with details when you get this resolved!

Cheers

Edit: I just looked at the 1800 blinker circuit at that link and notice it uses a 3 terminal FE, but the third terminal is "P" for panel (indicator). This is just and example of the many variations of FE and wiring out there...all three terminal FEs are not created equal...double (no triple!)check everything! Yes, I read where you said the "LED compatible" three term FE had a chassis wire, and I would also expect it to work, but something is clearly still not right...

Thanks, Ron Kwas!

I’ll check the link you provided and see what the schematics are in my car. I’ve also ordered another LED-compatible relay, but this one without any ground wiring. I just read somewhere that with an extra relay for the emergency flashers, it may have something to do with interrupting the turn-signal current flow, so I’ll have to check on that.

Will keep you all posted.

-DS

Does the new relay output a constant 12vdc or is it phased at something like 480 Hz? The reason I ask is because I’m currently in the middle of converting the instrument lighting in my 1800 to Dimmable LEDs with an LED dimmer that uses a phased output. The bulbs would not work when grounded through the chassis like the incandescents were. So I had to mod the light sockets to break the chassis ground and run a dedicated ground from the bulbs back to the dimmer. That might be why your relay has a separate ground terminal????
--
Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)

Another thing I forgot to mention, although I don’t think it’s what is causing your problem, is that the LEDs that I’m using are polarity sensitive. I don’t know if all DC LEDs are that way or if it is just the dimmable ones or what. So I found myself having to rotate some of them in their sockets to get them to illuminate. I thought I’d just throw that out there as food for thought.
--
Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)

Hi Chris Mullet:

I have not gotten around to thinking of making the conversion of the instrument cluster into dimmable LEDs, so I’m afraid I cannot help give advice.

I have not tried OHM-testing of the current to the turn-signal LEDs but I’m positive that it was a steady current, not phasing out.

I’ve tried reverse polarity with the new LED flasher relay but all I got was having all the turn signals blink as if the emergency flashers were engaged.

-DS