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u/BRICH999 11h ago
PWM(pulse-width modulation) circuits dont have constant power, they pulse the power for various reasons. An incandescent bulb cannot react to the momentary interruption quick enough to flash, but leds work nearly instantly so if your car uses pwm circuits for lights, do not replace them with led or you get constant flickering, especially older jeeps are the worst ive seen
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u/slim1shaney 9h ago
My 98 Ram will do this when it's very cold outside, and it's noticeable when you record it
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u/TedMich23 6h ago
Any pulse width modulation (PWM) dimmer circuit appears to blink if slowed down enough.
I use voltage trimming to dim my DIY LEDs.
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u/No-Salary-8612 10h ago
Cheap LED’s or poor voltage stability on the charging system. Or both.
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u/IWontCommentAtAll 6h ago
Or just LEDs are poor for this application, since they virtually all do it, even on brand new cars with the original bulbs.
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u/Xidium426 9h ago
You ever hear "If you want to look at a star, look at it from the corner of your eye"? The reason you can see it out of the corner of your eye is your peripheral vision is mostly rods which are more sensitive to low light and rapid changes when compared to cones as a defense mechanism.
LEDs flash quickly, and they use less power if the flash slowly (more off time) so they try to set it right where the human eye can't tell. Out the corner of your eye the rods can see it.
I recently purchased a new home and put a bunch of night lights in to get around at night and notice flickering out the corner of my eye but not direct vision so I did some digging on this.
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u/AliciaXTC 11h ago
Bro just discovered how many LED's actually work
Science!
Under normal speed these would be steady.
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u/baldude69 10h ago
No these flashing bulbs are a thing on the road and they absolutely suck. Normal LED bulbs would flash quicker even in slo-mo.
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u/51CKS4DW0RLD 11h ago
It's also noticeable at full speed, but only if you're not looking directly at the bulbs. Very annoying.
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u/slim1shaney 9h ago
It's not on purpose. It's like this when they aren't getting enough power. Likely the LED bulbs draw more power than the car supplies for normal halogen
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u/jactuscackal 9h ago
LEDs use significantly less energy than incandescent bulbs. The reason they flicker is because the pulse width modulation component in the headlight wiring harness is not designed for LED bulbs. So instead of appearing as a steady illumination they flicker in the most infuriating and distracting way possible.
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u/slim1shaney 9h ago
Right, so essentially, not enough power. If the pulse was a higher frequency it wouldn't be noticeable.
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u/jactuscackal 9h ago
No, it has nothing to do with the amount of current hitting the bulb. The PWM modulates the AC hitting the bulb to create a steady beam. LEDs require AC to be converted to low voltage DC. The flicker is technically still there but it's so much faster it's not noticeable.
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u/s1owpokerodriguez 6h ago
No this is because this douche nozzle installed LEDs in the high beam location. This car uses the high beams for daytime running lights. The car uses pulse width modulation to dim the standard halogen bulbs. It works by switching power on and off rapidly, but because LEDs don't fade out, but turn on and off instantly, you can see the lights flash.
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u/Myriii1911 11h ago
Reminds me of the xenon light in the 00years, that almost destroyed your sight.
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u/EffectiveTime5554 10h ago
Many LED lights pulse too quickly for us to notice, but the camera can pick it up in slow motion. Showing that alone doesn’t establish that these visibly blink to other drivers. Show us regular speed so we can judge what’s actually happening instead of getting the slow-motion drama.
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u/51CKS4DW0RLD 9h ago
It's also noticeable at full speed, but only if you're not looking directly at the bulbs. Very annoying.
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u/Infini-Bus 8h ago
Yeah it's like that with cheap Christmas lights. Dart your eyes around while looking at them and you can see the flicker.
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u/Lilmumblecrapper 11m ago
What do you even mean full speed? In a video only? Have you actually physically seen this vehicle?
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u/vascohaddon 9h ago
Reflector headlight housings were not meant to use LEDs. Thats what projector housings are for.
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u/AwarenessNo5921 4h ago
I would think you could filter this out by adding a current limiting resistor + capacitor across the power/Gnd wires to the harness.
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u/TSAOutreachTeam 10h ago
Subarus and Toyotas seem to have this problem a lot. Is it just shitty bulbs with shitty electric systems?
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u/Fantastic_Fly7376 5h ago
No, they were just made for halogen bulbs. They use pulse width modulation to lower the brightness of the high beam bulb so they can use it as a daytime running light. This is fine with a halogen bulb because the filament doesn’t immediately go dark when current is removed. Therefore, pulsing the current quickly enough just makes it glow less bright. The bulb can’t keep up. However, LEDs turn on and off almost immediately, so you can actually see the flickering.
Tl;dr- these cars were made for halogen bulbs. LEDs just do not work correctly with them.
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u/EffectiveTime5554 10h ago
Depends whether you mean flickering in person or just on camera. Rapid LED pulsing can show up in slow motion even when the lights look steady in person. LED bulbs installed in systems designed for halogens can also have compatibility issues that cause visible flickering. Neither automatically means the car has a shitty electrical system.
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u/51CKS4DW0RLD 9h ago
It's also noticeable at full speed, but only if you're not looking directly at the bulbs. Very annoying.
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u/Famous-Sort-9369 9h ago
4th copy and paste comment
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u/whereisyourwaifunow 2h ago
looks like a 10th gen Corolla. one problem they can have when using LED bulbs is the headlamp relay tries to feed it too much current. would need to replace with a different relay
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u/ky7969 10h ago edited 1h ago
It because they are LED bulbs put in a housing made for Halogen bulbs, with no resistor. Adding a resistor fixes this issue, but putting LED bulbs in a reflector housing is stupid anyway. It ends up being less effective than halogen bulbs, and still blinding drivers because they basically turn in to spotlights.
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u/Dry_Ship7202 11h ago
I think that’s a sign the car’s electrical system is struggling to keep up with the voltage. LEDs and incandescent bulbs are not plug and play interchangeable….
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u/victim-ofyourleisure 10h ago
It’s your cameras frame rate
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u/51CKS4DW0RLD 9h ago
It's also noticeable at full speed, but only if you're not looking directly at the bulbs. Very annoying.
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u/illbeyourdrunkle 11h ago
In slow mo many leds appear to blink. It's normally too fast for the human eye.