JMEufemia

Hello all,

I recently replaced all of my exterior bulbs minus the headlights with LEDs. I discovered that with the stock flashers, the signals/hazards would not flash as quickly as the incandescent bulbs that were in originally. Then I got replacement mechanical flashers and when installed nothing worked, they didn't even turn on. Then I installed a stock flasher into the turn signals and a mechanical flasher into the hazards and the hazards now flash as expected but the turn signals would not flash for about 3-5 seconds and then flash very slowly. Anyone run into this before? I've heard of hyperflash and I can't for the life of me figure out why they would be flashing so slow. I also can't figure out why the mechanical flashers would not work with the turn signals but function perfectly with the hazards. I was thinking of getting load resistors for the turn signals, but I'm not sure what to do. Any input would be helpful thanks.

Steve83

The flasher works by heating itself up, and then tripping (like a common circuit breaker) and resetting itself. It uses a TINY amount of current to heat itself, when the lights are off - that current isn't enough to light the stock bulbs, but those bulbs have low enough resistance to allow that current to flow.

LEDs have VASTLY higher resistance, so they don't allow that current to flow. "Load" resistors allow it, even with LEDs. But they also waste a lot of electricity as heat, so IMO it's a waste to use LEDs & resistors. To me, it makes more sense to just put a couple of normal bulbs back in - just enough to make the flasher work.

You can try a solid-state flasher (which is designed to use even-less current than the stock flasher), but it still may not work right, depending on the LEDs you have. A better fix is to use a 3-terminal (or 3-wire) flasher, which doesn't rely on the lighting circuit's resistance to work - it has a dedicated ground (the 3rd terminal). I haven't created this problem yet on any of my vehicles, so I haven't had to find such a flasher yet. But this one will do it (read the Brian G. review), and it's nearly PnP:
Just connect that extra wire to a true ground. You might have to extend it to reach one of the green screws in the driver's kick, between the e-brake pedal & the door.

BLDTruth

As Steve mentioned, the flashers require a certain amount of current to flow through them in order to work properly - so the reason you see them working properly with the hazards but not the regular turn signals is because when you have the hazards on, it pulls current through all 4 bulbs which is enough to trip the flasher and get it to work properly. The only work around to this is to add electronic flashers (the correct ones) or to add load resistors on your tail lights.

One other thing to check - if you have cruise control, then you most likely need to add load resistors onto the tail lights. The cruise control will not engage otherwise, because cruise will not engage with a brake light bulb burned out, and when there is an LED in there without a load resistor, it thinks the brake bulb is burnt out. At least this was the case on my truck, specs are in my signature. You place the load resistor on the line that is responsible for the turn signal/brake - the other power wire going to the tail lamp is the running light wire. This way the resistor only heats up when you are braking or using the turn signal, and not ALL the time when you have your regular lights on.

Electronic flashers are not necessary if you put the load resistors on, but I ended up getting them anyways because the thermal flashers always end up blinking in an irregular pattern, and they are very quiet. Electronic flashers blink on and off with perfect rhythm and they are much louder than the thermals, which is great for peeps like me who listen to their music loud and don't want to be the guy rolling on the highway with his turn signal still blaring. The ones Steve linked will probably work, I ended up getting , which is basically the same model only they are non-polar. The only downside to them is that they click 1-2 times more than the bulb flashes when you turn them off. It's a minor annoyance that I don't even notice any more.