Will LEDs make my flasher wonky?

I have no fewer than 4 bulbs blown on my Fordzda Branger.  I was looking on Amazon and they have lots of cheap LED replacements.

I upgraded to an electronic flasher (the stock thermal flasher took a dump).  Will it make my flasher go nuts?

Oh, and do I remember correctly that I can use a 3157 instead of a 3156 but not the other way around?  Just asking because they're cheaper in bulk and the truck uses a mix of 3156 and 3157.  I'm thinking about just getting ten 3157s

Since you have an electronic flasher, it should be fine. A thermal flasher would flash faster as the load goes down.

Ok.  I just know that I had an electronic flasher in my F150 and it would flash funny if a bulb blew.  I guess I'll try it.

Depends on whether or not your circuit is smart enough to look for the resistance of the bulbs as an indicator that they're working. I don't think your truck is that smart. 

They will not flash correctly unless you ad resistors inline. 

If you've upgraded to an electronic flasher it Should be ok. 

If in particular it's rear globes you're having problems with, it may be similar to the earlier b series earth fault. The earth/s for the rear lights were bolted to the top of the rear crossmember where the spare tyre carrier is, theyd end up corroded and crusty and not make a decent connection resulting in blown globes or feedback through other light circuts.

Another earlier b series light fault was the dimmer unit would fail and it'd cause headaches with lights doing weird stuff. Not sure if that's something that they improved over the years or not. 

mazdeuce - Seth said:

Depends on whether or not your circuit is smart enough to look for the resistance of the bulbs as an indicator that they're working. I don't think your truck is that smart. 

I have a remarkably dumb truck :)  1994 Mazda B4000.

daeman said:

If you've upgraded to an electronic flasher it Should be ok. 

If in particular it's rear globes you're having problems with, it may be similar to the earlier b series earth fault. The earth/s for the rear lights were bolted to the top of the rear crossmember where the spare tyre carrier is, theyd end up corroded and crusty and not make a decent connection resulting in blown globes or feedback through other light circuts.

Another earlier b series light fault was the dimmer unit would fail and it'd cause headaches with lights doing weird stuff. Not sure if that's something that they improved over the years or not. 

I'm not having any issues right now, other than several lamps burnt out.  The grounds are good, I just had one side that got water in the taillight housing and the glass broke on a couple bulbs.  Both front side markers are blown but ground tests good.  0.2 ohms to battery negative.  I know that I'm not supposed to have issues with resistance and an electronic flasher, I just recall that my F150 with an electronic flasher would flash fast if a turn signal bulb was blown.

I ordered the LEDs.  I am doing the whole truck inside and out (except for dash) for about $35.  I guess we'll find out.

In my experience from most likely to least likely flasher module to have a problem with leds:

2 terminal thermal

3 terminal thermal 

2 terminal electronic 

3 terminal electronic 

Anything with more than 3 terminals

Your old Ford was probably 2 terminal, but your Mazda is most likely a 3.

I just replaced the flasher and I can't recall, but likely a 3 terminal.

Thanks for the tip

And here is the verdict.

The 4-ways on the old 2-pole thermal flasher work great.  The turn signals (on a 2-pole electronic flasher) worked fine last night when I installed them, but today they don't.  They won't flash, and they don't even come on when I move the stalk.  If I rapidly move the stick up and down, sometimes they will flash for a split second.  I drove to work today with a very cold arm out the window.

I guess I'll try swapping the thermal and the electronic, but then I anticipate problems with turn signals when I hook up a trailer.  Oh well, back to the drawing board.  Is there another flasher I should try?  Or is there a resistor I should put in somewhere?

There are electronic flashers meant for LED lights, that would be the easiest route. Resistors can be done, but I would rather put in one flasher than 4 resistors.

81cpcamaro said:

There are electronic flashers meant for LED lights, that would be the easiest route. Resistors can be done, but I would rather put in one flasher than 4 resistors.

I assumed a person could do one resistor in the wire from the flasher.

In reply to Curtis :

Aren't they supposed to flash fast to let you know there's a problem?

One more thing may be worth a try before resorting to resistor packs, an electronic flasher with an external ground wire:

https://www.amazon.com/United-Pacific-12V-Led-Flasher/dp/B004O1YTLW

If that doesn't do it, you'll need resistor packs, you may get away with 1 per side with an electronic flasher but 1 per bulb is recommended.

purplepeopleeater said:

In reply to Curtis :

Aren't they supposed to flash fast to let you know there's a problem?

 

I have experienced so many different things that I don't think there is a consensus.  The little green martian that lives inside the flasher just gets confused.

The odd thing is, the thermal flasher for the 4-ways works perfectly with the LEDs.  It flashes at the same rate as before with the tungsten bulbs.  The electronic flasher in my old F150 would blink fast if one of the bulbs was blown.

Yesterday I tried an experiment.  I swapped the thermal and electronic flashers so that the E-flasher was on the 4-ways and the thermal was on the turn signals.  Neither function worked.  At all.  Not even solid lights.  The indicator on the dash comes on very dim while it is in the turn position, but no light at the LEDs.  So I put them back in their original positions so I at least have 4-ways.

I ordered one of those flashers with a ground, but it won't be here until next week.  I think for now I'll put tungsten bulbs back in the front temporarily so I can actually have turn signals until it gets here.