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Touring Plus
Discussion Starter · #1 ·
Morning all, long time reader first time poster. We've had a 2019 touring plus for about 3 years now and have been loving it. Recently I decided to finally do something about the terrible low beam halogen lights and replace them with leds. I did this on my 2014 Mazda 6 years ago and had great luck. I've never been a fan of using some ridiculous 20k plus lumen bulb, those can be blinding even if aimed right, so I went with these.

The cutoff and color are great, but there's an odd issue I haven't seen before. With the lights on and the engine off they're great, but when you start the car they start to flicker ever so slightly and are just a bit dimmer. It's almost hard to see, but it's there. Anyone else run into this? I'm thinking about trying another brand but maybe there's another solution. I've seen people use load resistors and canbus decoders on other vehicles but am not sure if that would help me here. Thanks.

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The aftermarket light emitting diode (LED) bulbs like those normally integrate the driver electronics for the LED "chips" (that create the light) into the base of the bulb assembly. Depending on the actual LED chips they use, there may be some type of voltage regulation, for example taking the vehicle's 12 volt and reducing to 5 volts used by the actual LED chips.

When you turn the headlights on but don't have the engine running (specifically for gas models) the bulbs are probably getting 12.2 to 12.5 volts from the battery. When you start the engine, the alternator will often output a higher voltage and keep the electrical system at a slightly higher 13.7 to 14.5 volts on most cars, depending on a number of conditions like electrical load, ambient temps (colder batteries require more voltage to charge and keep charged, etc.).

Without knowing the what type of internal electronics are used to drive the actual LED chips, it could be doing a DC-to-DC conversion (direct current; what the car 12 volt system uses unlike household alternating current (AC)) with a step-down transformer, but more commonly they'll use a microprocessor. If it doesn't produce clean outpu voltage, the LEDs could flicker.

Also if these aftermarket bulbs perform any internal light output control to try to keep a stable, consistent light output with changing input voltage, the electronics in the bulb might be using pulse-width modulation (PCM) to drive the LED chips. This flickers the LED at a frequency that's "supposed" to be imperceptible to the human eye, but some people are more sensitive and bad designs may cause noticeable flicker.

Probably not your case, but if you use these aftermarket bulbs in a vehicle that uses a reduced high-beam voltage for a daytime running light (DRL) when the car is running, this often causes problems with the LED driver electronics.

Also some really poor quality aftermarket LED bulbs that try to place the LED chips in a similar position as the conventional bulb's tungsten filament often won't have enough metal for a good heatsink to keep the LED chips cool (high-power LEDs create a lot of waste heat, just not as much as a conventional halogen bulb). When the chips and/or electronic drivers in the bulb's base get too hot, they may not perform correctly.

I'd suggest checking the van's voltage with the engine off and then running, but if it is too far off when running from what the engine control computer commands (as it controls the alternator output), you'd probably already have seen a check engine light. Unless there's some other problem with the headlight wiring harness and/or ground to the vehicle, I'd suspect you might have got a bad set of bulbs. If they're from Amazon, maybe reach out to the seller or return for a replacement set.
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