Resistor Question with 2020 OEM LED Conversion and Meso Total Taillight

Hello,

I am thinking about upgrading my 2020 Toyota SR Headlights to the OEM LED headlights. I already know about getting the conversion harness V2

The issue is, I already have MESO Custom Total Taillight Stage 1, with 2, 10 Ohm resistors. The creator of the conversion harness V2 said he is not sure if 2 10 Ohm resistors would work with the included front resistors apart of his conversion kit, or if I don’t need resistors at all.


Does anyone have resistors from MESO for their taillights and then another set of resistors for the front headlights with the Conversion Harness? If so, is anyone experiencing any issues with hyper flash, etc?

 

I have the TRD led headlights with the conversion harness in my '19 SR5 along with the Meso stage 1 taillights without any resistors and 99% of the time I don't get any hyper flash. You should be fine with the resistors you have.

Yes, on rare occasions mine will hyper flash but it's so infrequent I haven't bothered to do anything about it even though I have the resistors, in a box, sitting on a shelf in my garage.

 

@daveeasa and @Puppypunter would have a better idea as they are the geniuses behind conversion harnesses for OEL LED headlights. The @ alerted them.

 

You try things out and see, they plug in or don't, use of resistors is optional, you can do 25's, 15's, etc.

Each truck is a bit different.

 

@GP2002 and I have been discussing this privately, but it makes sense to put it here as well for the person who googles this in 2029….

First of all, how is 2029? Are our robot overlords treating us well? But I digress….

The issue with these truck and hyperflash is that they defy any math that I know. There is a small window between “not enough” resistance (hyperflash will happen) and “too much” resistance (the turn signal will flash once, then lock up and not flash again). The “too much” line seems like a more defined line, but it’s still hard to say where that line is. This is made more complicated by the fact that on these headlight conversions, we are trying to give it just enough resistance for that fraction of a second when the relay is turning over once that happens, then the OEM LED lights have built in resistance. This is enough to drive someone crazy, but then you add resistors in the back to the equation? Maddening! The good news tends to be that the amount of resistance required does seem to be low. How low, I am not sure, but on my personal truck (which does have the OEM LEDs and the equivalent of the Meso total tails running VLED V6 bulbs) I run two 25 Ohm resistors in series on each side. So effectively 50 Ohm resistors. The front turn signals in my case are taken out of the equation totally (I use relays triggered by the rear turns to drive the front turns and way too many added blinking lights as well), so the 50Ω is the only load in the front, and no added resistors in the back. I do know that the 25Ω resistors I include can cause issues when combined with 6Ω in the back, but 15Ω in the back works fine. So 10Ω being the middle ground, I’m not sure. I suspect you’d be okay keeping the 10’s in the rear and not running the 25s in the front, but that is a guess (one the OP and I have discussed testing this theory, so I’ll update as I get info).
As a side note, just so people get an idea why I say the math doesn’t add up to me, here is where it can get weird. If you have 25Ω in the front, 15Ω in the back, it will work. But if you swap the two (so 25s in the rear, 15s in the front) it will be too much and seize up. I know wire length comes into account, but really?! It’s the same load! And it isn’t that it is monitoring the four corners separately, it is still just looking at right/left. The sweet spot seems to be the larger resistors in the rear if needed. I personally prefer keeping the resistance low as possible (mainly for heat reasons). Even better, I’d rather run two 6Ω in series than one 12Ω (since it quarters the load on each, so heat distribution is improved greatly), but I’m weird and I’ve accepted that. Just like I’ve accepted living under our new AI powered masters….

 

I've been through several iterations of LED lighting and this is what I encountered:

Stock halogen headlights with LED signals, stock tail lights with all LED bulbs, stock mirror lights: Resistors required.
Stock halogen headlights with LED signals, stock tail lights with all LED bulbs, MESO mirror lights: Resistors NOT required.
Stock halogen headlights with LED signals, MESO stage 2 tail lights with all LED bulbs, MESO mirror lights: Resistors NOT required.
Morimoto XB headlights, MESO stage 2 tail lights with all LED bulbs, MESO mirror lights: Resistors NOT required.

I had resistors in place when I added the MESO mirror lights and the turn signal circuit would go into an error state and only flash once because it was overloaded. Once I removed the resistors in that (and future) configurations, the signals flashed correctly.