LED Tail Lights - Adding Resistors

[Pilotdave]

Synchro909, the turn signals are combined with the brake light in the tail light units.

Patrick, the front directional lights use incandescent bulbs. There are no indications of the candle power or wattage on them, however, and thus far I haven't been able to locate a source for higher power bulbs.

The reason the resistor is connected in parallel is that doing so lowers the resistance in the directional circuit. Less resistance translates into higher current flow which is what the flasher unit needs to slow down the flash rate.

I have now run a wire from the battery ground point to provide a ground point at the tail lights so don't need to be concerned about a faulty ground for them or the resistor. Still getting the same fast flash rate. This implies that the load resistor has too high a R value - I think!

Some ideas:
1. find a load resistor with a smaller R value - or perhaps double up the load resistors to effectively create a lower R value.
2. Find an electronic flasher that actually works with 6v, +ground systems.

Other ideas would be really welcome!

Dave

[Bob Johnson]

Originally Posted by nkaminar

Bob, the resistors are meant to cure hyperflashing. I know it does not sound logical but that is what they are for. See https://www.superbrightleds.com/blog...rflashing/275/.

My bad ignore my previous post


Bob

[nkaminar]

Pilot Dave, I think you are on the right track. Remember to check the pinouts on any LED flasher you get.

[Pilotdave]

An update. I switched out the (thermal) flasher unit to a different brand I had on hand. The flash rate is now quite acceptable. Interestingly, the flash rate is identical on both left (includes resistor) and right (no resistor). I conclude that, somehow, the added resistor is not making proper contact on one lead or the other.

Thanks for all your suggestions......sometimes I guess it pays to try the simplest thing, even if it's illogical! Apparently it's too much to expect that 535 flashers are all the same!

One more test to try: I'll pull the incandescent bulb in the front flasher to see if its absence makes any difference.

[Patrick L.]

There is a lot of info on certain website regarding bulb candle power. One is bulbtown.com.


Not all flashers are created equal. Its best to find a NOS somewhere. The new chinese units are junk.

[Merc Cruzer]

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Originally Posted by bruceincam

Dave, I've done the same as you with a 12V neg ground conversion. I'm using a 50W, 6 ohm resistor at each LED tail light. The results are acceptable and what I would call "normal". Same Signal Stat system. Sound like mine are wired just as you describe --- one end to the turn signal wire and the other end to ground. Maybe add a little resistance -- 6.5 ohms isn't much.

Re: LED Tail Lights - Adding Resistors
I believe that the resistors are only needed if the flasher flashes too SLOW. The resistor increases the current that goes through the bi-metal switch which results in it heating up faster increasing the flash rate.

Bob


I have the "Hyper Flash" situation, so my question is rather than putting a 50 watt 6 ohm resistor (or any resistor) on each side, why not just put a single 50 watt 6 ohm resistor on the load side of the flasher? Or am I over simplifying?

[SwampLedge]

“Hyper-flashing” refers to modern vehicles where the directional s are controlled by a computer module, not a traditional old style bimetallic flasher. With a traditional flasher, the higher the current draw, the faster the flash. With the computer control flasher, the resistors in parallel with the LED increase current draw so that the computer (which expects incandescent bulbs) doesn’t read the lower current draw as a burned out bulb and initiate hyper flashing to alert the driver.

[Merc Cruzer]

Originally Posted by SwampLedge

“Hyper-flashing” refers to modern vehicles where the directional s are controlled by a computer module, not a traditional old style bimetallic flasher. With a traditional flasher, the higher the current draw, the faster the flash. With the computer control flasher, the resistors in parallel with the LED increase current draw so that the computer (which expects incandescent bulbs) doesn’t read the lower current draw as a burned out bulb and initiate hyper flashing to alert the driver.

Sorry for the misuse of the term. It should have been "(Hyperflashing)." It came from this article:

https://www.superbrightleds.com/blog...rflashing.html

[SwampLedge]

No need for an apology. :-) I was just trying to help with the confusion that seemed to exist earlier in this thread. If you have LEDs and a conventional flasher, and the lights flash too slowly, then yes, a resistor in parallel with the lights could help. But if yours are flashing too quickly, that is a situation that used to be common when adding trailer lights with a conventional flasher. The best solution is an electronic flasher that flashes at the same rate regardless of load. I used one of these on an old Ford 9N tractor for hazard lights with no issues.

[Merc Cruzer]

Originally Posted by SwampLedge

No need for an apology. :-) I was just trying to help with the confusion that seemed to exist earlier in this thread. If you have LEDs and a conventional flasher, and the lights flash too slowly, then yes, a resistor in parallel with the lights could help. But if yours are flashing too quickly, that is a situation that used to be common when adding trailer lights with a conventional flasher. The best solution is an electronic flasher that flashes at the same rate regardless of load. I used one of these on an old Ford 9N tractor for hazard lights with no issues.

Interesting. When I solder two 1154 bulbs together and use the flasher, it works perfectly (correct resistance tot he flasher). But when I install it in the car, where most of the bulbs have been replaces with LED's, it flashes way to fast. That would seem to say I need something that would simulate a higher resistance (wattage demand). Hence the reason I was asking about putting a 50 watt 8 ohm resister between the load side of the flasher and the turn signal switch.

Do you have a mfg and flasher number?

The first picture was a bit too generic. Thought I would add a few more, vehicle specific.

[SwampLedge]

Maybe try this one-> https://www.ledlight.com/flasher-6-v...e-chassis.aspx

[rotorwrench]

Flashers units were designed to operated with standard type flasher/brake light bulbs such as the 1154 for the 6-volt and 1157 for 12-volt. Modern LEDs have very little current draw to make a normal bi-metallic signal stat operate. Even when systems have two LEDs flashing at the same time (ie front and rear turn), the system signal stat senses low current draw much similar to one bulb being burned out of a normal incandescent set up.

Putting a resistor on the power input to the signal stat is going to draw current before the power ever gets to the flasher unit so it will be cutting power for it's operation. It may draw so much current that the bi-metallic can't even break the circuit as it should. At rest, the bi-metallic is in closed position with no ground path so the turn signal switch provides the rest of the circuit to make it function. Turn the signal on and power flows through from the flasher unit to the current draw which are what ever lamps chosen. If current draw is very low then the bi-metallic won't get as hot and can't open very far so it closes quicker and causes the overly fast signal rate. The bi-metallic has to have more current to pull it well farther apart to slow the breaker rate.

Since each side with a separate front and rear circuit flash at the same time, only one large resistor should be needed in that sides circuits to get the flasher unit to function as it should. Most are 6-Ohm 50-Watt so I'd start with that. Most diagrams I've seen have them in the tail light circuit connected in parallel between the circuit wire and a good ground on the frame. If it still hyper flashes then load resistors may be needed on all four corners.

If you don't want to mess with load resistors, the the electronic signal stat for LEDs would be the only other way to go.

[Merc Cruzer]

SwampLedge,

Thank you for the suggestion, I had been looking at that flasher previously, since all of the LED bulbs I have purchased, have come from ledlight in Phoenix (I am in Colorado so they are close). But I just couldn't let the issue go, before I was able to solve the original problem.

I have a Vintique flasher in the car and it has been performing as it should, throughout my replacing most of the bulbs, in the 53' Merc Pos Ground, with LED's from ledlight. There was no issue with "Hyper-flashing", prior to me getting around to replacing all the bulbs in the gauge cluster, to include the "turn signal indicators". A few days later I began experiencing the Hyper-flashing issue. Logic told me that I had finally reduced the load demand, down to the point the flasher would not perform as expected.

I looked into adding resistor(s) (in parallel) to the system to increase the load demand on the flasher unit. I even thought of adding a single resistor to the load side of the flasher wire. (most of the videos showing adding the resistors to each side of the turn signal system, since in the newer cars, the flasher is not designed to add a separate circuit to the system. Lucky for me, the age of the car, provided me with an exposed three prong flasher (replaced the original square 2 prong flasher with a newer 3 prong round canister type). The three prong flasher, had an additional prong, in the center, that went to the "pilot" bulb (a single bulb in the dash of newer cars, that just tells you the turn signals are on, not which one), that replace the two separate indicators on the older dashes).

I then thought, well, if I have reduced the the demand down too low, why not just increase the demand again. I attached a jumper wire to a new bulb, attached to the "pilot" prong on the flasher and then grounded the bulb. Cycled both flashers and they worked correctly again. At that point I just eliminated the bulb and grounded the wire from the "pilot" prong, and the issue was resolved, by increasing the demand.

In all likelihood, I will go ahead and buy the electronic flasher from ledlight, but I needed to resolve the issue before I ordered it. My Engineering degree, from back in 1971, still requires me to "think through the problem, and solve the issue" Thank you all for your suggestions and tolerance, during this journey.

[Merc Cruzer]

rotorwrench & SwampLedge,

As an FYI, I just order the flasher from ledlight. I was able to solve the issue to my satisfaction, but the correct flasher is a better resolution in the long run. The challenge was fun for me.

Thank you both.

[AL in NY]

You don't need to add resistors................see post #15.

[Merc Cruzer]

Originally Posted by AL in NY

You don't need to add resistors................see post #15.

As rotorwrench said: "If you don't want to mess with load resistors then the electronic signal stat for LEDs would be the only other way to go."

That's why I bought the flasher from ledlight.

[Merc Cruzer]

Originally Posted by Synchro909

What has changing the tail lights got to do with the turn indicators?

Pilotdave
Senior Member
Default Re: LED Tail Lights - Adding Resistors
Synchro909, the turn signals are combined with the brake light in the tail light units.


Not sure about the "Synchro909" but in my 53' Merc, the brake light, turn signal and tail light, are all one bulb.

[katy]

Not sure about the "Synchro909" but in my 53' Merc, the brake light, turn signal and tail light, are all one bulb.

That's common, one bulb w/2 filaments, one for tail lights, the other for brake light or turn signal, depending on the selection on the turn signal controller.

[Synchro909]

Originally Posted by katy

That's common, one bulb w/2 filaments, one for tail lights, the other for brake light or turn signal, depending on the selection on the turn signal controller.

Common there maybe but banned here for the last 65 or so years.