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Electrical guys... Blinker relay question

777 Views 9 Replies 4 Participants Last post by  GreenEnvy
with my new undertail it requires I get some new rear turn signals.
I've got a nice set of LED signals that are actually designed as running lights or those wiper nozzles people use on cars (and dont worry they are not blue, they are just red/green)

When I wire them up, and hit the blinker or hazards, the led's come on but do not flash. If I wire the stock lights back on, it flashes fine.

Measuring the resistance across the led circuit (from ground to the +12 line) its like 80K Ohms. Im guessing since the resistance is so high the relay is not able to have the lights blink???

If so, do I need a different relay? the current one is a fairly standard one, a 552.

Any ideas? suggestions anyone?
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An aftermarket solid state relay will usually make it flash at a normal rate. It will take a two terminal relay. You can get one at Auto Zone for about $10.
Lee, do you have the original relay or an aftermarket electronic one? ...Sorry, I haven't played with this stuff in a while and am not sure of the 552.

As for your resistance theories, it has some merrit. See the regular lights have a resistance of like... ?? Lets say 5 ohms. 12 volts, 5 ohms = 2 amps. Now you've got 12 volts and 80K ohms. 12 volts, 80K ohms = 0.15 milliamps. Since most relays work by having some type of capacitance in them, your new set up just isn't draining that off which is what needs to happen. (It's getting late and this is just a thought...)

What I would suggest is firstly trying an electronic relay...
If you've already done that with no success then try adding in a couple 2 to 5 ohm resistors into your circuit... (For the best results measure the resistance of the original signals and try to get a resistor with a value close to that number.) If you put one in parallel with each "turn signal" (the LED's you've got) you will effectively lower the total resistance of each turn signal circuit to JUST under that value and thus allowing more current to flow which I think should solve your problemo!

Let me know how you make out, or give me a shout tomorrow... Boyracer's got the number.
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... I should add that IF you need to go the route of the resistors, you need to keep the wattage in mind. 12 volts, 10 ohm resistor = 1 amp. 12 volts, 1 amp = 12 watts.

So, hopefully that solid state electronic relay will do the trick for ya!
did you measure the circuit with a diode checker or a regular ohm meter? typical diodes require .7volts for bias before you enable the circuit and are able to measure it. put a small resistor in parallel with each LED so the relay isn't looking at the diodes, but looking at a nominal resistance. keep in mind the normal bulbs' resistance is not very great either,
one8t, he doesn't just have diodes in the circuit...
Store bought LEDs (made for automotive applications) have resistors added to them already as there is no such thing as a 12 volt LED, they need a current limiting resistor which the manufacturer has already taken care of... Also, he's not dealing with regular diodes, LEDs typically require in the area of 3 to 5 volts for "biasing" (point where they'll light up). Plus when adding resistors to a 12 volt circuit you have to watch the wattage they'll be exposed to or all that you will have is a puff of smoke.

CDN, I was at Canadian Tire this morning purchasing another tool chest :) ... Anyways, I saw the 552 relay you spoke of and it's more the "mechanical" type. Buy the #-terminal equivalent (I think it was a 2 terminal?) in the electronic type for like $7.99 and you should be blinkin'!
I picked up the electric relay this afternoon, it worked but blink was very slow. I added a 100ohm resister in parallel, now its got a normal blink speed.

Only remaining issue, and its not that big of an issue, is the lights dont blink on/off/on/off, they blink on/brighter/on/brighter. I'd prefer it to be totally off, but it still works. I'll post a pic shortly..
Heres some quick photos, sorry they are all dark, its after midnight...

First pic is blinker when its engaged and dim, second shot it is bright (flash). The other 2 pics are closeups of the unit itself. First shows the dual LED's, one green one red. second is a shot of it off.

Lee, I am liking the looks of that!! [8D] ...Still brainstorming as to why it's operating the way it is.[?]

Are the blinkers on dimly even when you haven't signalled for blinkers? In other words are they on ALL the time or just after you select left or right or hazards? (I'm assuming No.)
When the blinkers were operating slow (before you added resistance) were they going completely off?
Have you tried a smaller resistor? (More like 10 or 15 ohms with an appropriate wattage... I think you still may not be drawing quite enough current to drain the capacitance from the relay.)

One other suggestion, you may think it's dumb but...
What do you think about putting your tail light integrator back in? Keep the signal blinkers you've got AND add in the integrator. You'd have to have your blinkers on the input side of the integrator so as the blinkers don't both go on when you hit the brakes... but the tail light bulb then being in the signaling circuit may solve your current (no pun intended) ;) problem.
...like I said, just a thought.
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I'll try a smaller resistor and see.
When I am not signalling at all, the LED's are totally off, they just come on when I hit the blinker or hazards.

As for the integrator, I'll see if I can get it back from Mike. I dont want to run just the integrator, I dont think they are safe. I know I almost hit him a couple times because I could not tell he was turning.. Using it with the flushmounts could work though.
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