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· He's not mine
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I attempted to replace my side marker lights with LEDs, which draw less current. It did cause hyperflashing of the turn signals.


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Hey Jetfuel, heard from Kermit in the last year or so? PM
 

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So long as those LEDs have a CANBUS resistor in them (and a good resistor, some of the cheap eBay ones don't work) they will not rapid flash. Took me a few tries, but I found side indicator LEDs that don't trigger it.

Unfortunately the system uses current to determine if it needs to rapid flash. Too little current (a single LED can do the trick) and you'll get rapid flash. So getting a CANBUS LED isn't going to reduce the current on the system at all, but you shouldn't have to worry about bulb replacements anymore and to me they look aesthetically better too.

But yes, if the bulb in the side flasher goes out you'll get the rapid flash.
 
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· He's not mine
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some of the cheap eBay ones don't work)
Sometimes cheap doesn't mean inexpensive. Mine weren't. And, they came from a reputable source. Shame on you for suggesting I bought them on eBay, LOL.

It should be noted that LED swaps among smart 451's don't have universal results, for reasons I've never had explained ... not sure I've seen an attempt, other than maybe longer harness wires or other nonsense.

A prime example: I have LEDs in the rear with no problem. I tried them on the front turn signals and got hyperflashing. Other members have experimented with the exact opposite result, i.e. rear LEDs causing hyperflashing, but fronts not doing so.
 

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Oh I know you didn't get yours from eBay, I was referencing myself. :D Every LED I've bought so far either came from eBay or Amazon.

For whatever reason the electrical system in a smart is really finicky. I believe an additional problem is that no LED is created equal, even pairs of the same exact LEDs can be slightly different. There has to be a perfect balance or it rapid flashes. Something also makes me think that the "perfect balance" may be dependent on model years and perhaps rolling changes that aren't advertised. I myself haven't found the perfect balance yet. As of right now, these bulbs are LED:

- Dome light.
- Reverse lights.
- License plate lights.
- Parking lights.
- Third brake light.
- Side indicator lights.

I found the best way to prevent rapid flash in my car is to make sure every LED (even the license plate lights and the third brake light) has a resistor in them and get the highest power LED I can find for the application. CREE ones seem to work the best for me. The only lights currently not LED are the brake lights/taillights and the front turn indicators. I know I can get them LED and not get the rapid flash, but I'm not going to do it until a bulb blows. :)
 
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If you replace a bulb with an LED that has the resistor in it. I would think that the setup would draw just as much amperage as a regular bulb

I have had my side bulbs burn out and did not see any indications on the frequency of the turn signals....
 

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If you replace a bulb with an LED that has the resistor in it. I would think that the setup would draw just as much amperage as a regular bulb

I have had my side bulbs burn out and did not see any indications on the frequency of the turn signals....
That is correct. The system is expecting a certain amount of draw. If said draw is too low then it assumes the bulb is out.

Now, if one doesn't care about rapid flashing, then go ahead and replace everything with any cheap LED (a few people here have done just that). That said, when I did that with my car it caused strange side effects. Like, when I hit my brakes both my parking lamps and the license plate lamps dimly illuminated. When I turned on my right turn indicator the left brake light would very dimly flash, and vice versa. It's as if the power bleeds out into bulbs that shouldn't be running at the time.

Now that's an interesting observation too. When my side indicator on the left side went out it caused a rapid flash. I wonder why there's a lack of consistency among electrical systems in 451s?
 

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Had the back lights om my Century burn out (about 4 out of 8 bulbs) and it also did not affect the turn signals, but when the front right signal bulb quit working, I got the hyperflash.. doesn't make much sense, except tht the rear bulbs are on with the headlights so it might be a different circuit.

Got pulled over for a headlight on the smart, it had just went out as I saw it before I left from work, then at the first light I pulled up behind a van and noticed it was out. 15 miles later, I got pulled over.Of course I see dozens of cars with one light out, but I get pulled over....
 
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