Issue with 2021 5th Gen 4Runner mirror LED with rear turn LED

Today I installed a set of mirror LEDs as well as replaced the puddle's with LEDs. After installing I tested and the mirror LED turn strobe was awesome as well as puddle LED was much brighter than OEM bulb.

In addition to the interior & mirror LEDs, I also purchased a set of ALLA lighting 2800ml 7440 amber/yellow LEDs off Amazon along with a reverse LED from the same company. I also purchase a second set of amber/yellow LEDs to replace the amber bulb in my headlight.

The issue appears when I replaced the rear amber turn bulb with the amber/yellow LED.

When I turn the truck on to test, the new rear amber LED are very bright, which is good but two issues- they blink fast and the mirror LEDs sort of work 1/4 of the way. I replaced the rear amber LED with the OEM amber bulb and tested again. Now the mirror LEDs now work great again.

Note- while I purchase front headlight amber LEDs to replace OEM headlight amber bulbs, I never replaced them. As soon as I saw I had issues with the combination of mirror LED with rear amber LED I stopped and replaced the rear OEM amber bulb - didn't want to go through the labor of replacing the front OEM headlight amber bulb with the new amber LED because it looks like to do that requires removing the headlight. Which isn't a big deal to do just not sure if replacing that OEM headlight amber bulb will make a difference with the new mirror LED.

Anyway - I wanted to get some feedback from the forum before I send the new amber/yellow LEDs back to Amazon.

 

On our 4Runners the flasher function relies on the OEM incandescent bulbs to supply some resistance in the flashing circuit. When a bulb burns out the resistance in the circuit changes, the flashing rate increases, and you hear it, telling you a bulb has failed.

When LEDs are installed in a flashing circuit (turn signals) they have a very low On resistance and the flasher circuitry thinks a bulb is missing so it goes into this “hyper flash” mode.

Most automotive LED bulb vendors tell you about this in their website documentation and they offer you a solution. Which is to buy a high power low resistance resistor to install across the leads of the LED to fool the flasher. It’s kind of a messy solution. Some vendors sell turn signal LED bulbs that have the resistors bulb in so you don’t need to add any separate resistors. They advertise these as “CANBUS compatible”, which is not actually true. It just means there’s an extra resistor in there. One such outfit is LASFIT. That’s what I use. There are other bulbs that have built in resistors. Should be other threads on this forum (and the other 4R forum) that describe them.
LASFIT
For rears:
https://www.lasfit.com/products/lasfit-7440-7441-w21w-led-turn-signal-lights-canbus-error-free

For fronts:
https://www.lasfit.com/products/amber-amber-7443-led-turn-signal-light-bulb-anti-flickering?variant=21325353713748

 

Thanks for the explanation. I was able to contact the seller and get a set of load resistors.

 

And a side note is that the bulbs with the built in resistors will get hot, so their lifespan is much shorter. Diode Dynamics sells some kits with external resistors that can dissipate heat more efficiently.
With that being said, keep the oem bulbs around in the car, sooner rather than later you will need them.

 

That’s good. Here’s some info on installing the resistors. For the front ones you’ll need to install the resistor on the flasher filament wire to ground. Not the parking filament wire.
https://dammedia.osram.info/media/bin/osram-dam-13303201/Load Equalizer Installation Guide.pdf

https://youtu.be/ADKjG3Z2L5w

 

Thanks for clarifying which wire to use. As I was looking through all the options for resistors; one of the sellers had a schematic that showed this but it wasn’t clear that it was the front amber LED. The front LED is also used when the DRL are on. So the bulb is dimly light constantly which as has been pointed out; heat is an issue when switching to LED. This was a consideration when I purchased the resistors. In a comment on the listing for the LEDs I purchased; the seller responded to a question regarding the hyper flashing issue with their listing for the resistors. The watts and ohms for their listing was 50w & 60ohm axial. With that I searched across Amazon because their kit was $15 for just 2 resistors. These resistors are very common and I was able to find a kit compatible with my LEDs in a set of 10Pcs x 50w @ 60ohm in a aluminum case for $17. So not only was this a better buy but where the same size and design so should be just as easy to mount to a metal surface along each circuit.

I looked for ones that had the resistors built in but also thought about the heat issue and felt these where likely going to be issue prone in the long run.

Here’s a link to the kit I purchased.

10Pcs Car LED Load Resistors 50W 6Ohm Fix LED Bulb Fast Hyper Flash Turn Signal - Connect 1156, 1157, 3156, 3157, 7440, 7443

$19 10Pcs Car LED Load Resistors 50W 6Ohm Fix LED Bulb Fast Hyper Flash Turn Signal - Connect 1156, 1157, 3156, 3157, 7440, 7443

https://smile.amazon.com/dp/B07GQWN..._glt_fabc_7XR4FSHV90HZ87M497TH?_encoding=UTF8

Once I get these installed I’ll post some pics.

 

You only need resistors for bulbs that flash. For our 4Runners the rears just have two wires so that’s easy, and should be easy to mount the resistors to a metal surface. Do those first then test them.
The fronts have three wires so you have find the two you need. You access them from behind the fender liner, so that may be may be more of a pain to work in that tight space. Instructions are in your owner manual under Do-it-yourself maintenance.

As far as heat goes, yes the resistors get hot when flashing. But the LEDs bulbs don’t get super hot, the better ones are built with aluminum heat sinks.
They’re rather large and heavy so when you’re satisfied they all work put a *little* dab of a thick adhesive on the exterior of bulb base to socket base (not inside). Like shoe goo or clear E6000. This will help hold them in place and not pop out when you’re bouncing around off-road.

BTW, the hyper flashing of the rear turn signals and the exterior mirror ones you noticed was because they are driven off the same circuit. So installing the rear resistors (left and right) will take care of the mirrors too.

 

This was a schematic one of the load resistor vendors provided. Looks like it provides for both rear as well as front running light.