Before anything I just want to disable the factory drl feature on my Canadian 2008 ls600hl while I'll be keeping my led drl on my jdm fog lights so this is perfectly legal since I will still be having drl. On US car this can be done with Techstream but not on Canadian car and I don't want to go as far as to swap the BCM for a us spec one. On my subaru I just had to remove one pin on the drl relay and that did the trick while preserving my high beam since like the ls both drl and high beam share the same bulb. I do wish to preserve the high beam so just removing the bulb is not an option. I also have to keep in mind that the high beam is always on while the low beam are on although the light is not visible since the filter in the headlight assembly only let the infrared wave through as per the APCS specification (I suppose it supply 12v to the bulb in that mode). Since the car probably drop voltage to 6v or 9v in drl mode I was wondering if some kind of adapter existed that I could install inline that would not let current through unless it detect 12v or higher (similar to a 12v low voltage controller). That way this would disable drl while still preserving the high beam. I think converting the high beam to hid would also work since the ballast would probably not work with a current under 12v but I don't want to go that route either as it could mess up the APCS. I could try to install a relay that would cutoff the current when the fog drl are on but since I want and wired them to be always on that would not be desirable and I also don't want to install a dedicated switch to keep the install simple and automatic (and also the high beam would not work if the led drl are on). Last solution would be to sniff the can traffic with canutils on linux while disabling the drl on a us spec car and replay the packets on my Canadian car in case that it's only the menu that is disabled while the feature is still there but I don't have access to a us spec car either. So far the best solution I found so far would be something like this: Thanks for the help if anyone have additional ideas.

 

Measure voltage at the bulb to see if there is indeed a voltage drop to say 6 volts with the DRLs active. If you remove both high beam bulbs do you get a warning message? A circuit that cuts power when fed anything less than say 11 volts shouldn't be hard to make.

 

As far as I know , All NA cars lexus DRL function can be disabled in tech-stream. Because Its programed . I even checked NA service manuals and all state that DRL function can be turn-off in Customize option in Tech-stream. The sender is the BCM/Main body ecu. If you don't have that option your best bet is to get a EU LS600 BCM(AC temp will be in Celsius and no answer beep when un/locking) Or US( AC temp in fahrenheit then progrm it using tech-stream) BCM. Also imagine CAN sniffing 2 lines for keep on and keep off that a big task.

 

I checked with techstream and I have all those options except DRL. It's well known on toyota forums that you cannot do it with techstream on Canadian car, many have tried but the menu is just not there for toyota/lexus car. I'm pretty familiar with can sniffing so for me that would be easier than replacing the BCM but I would need someone to sniff the can and then send me a dump so I can manually push it to my car although it won't necessary work depending on what is different on a canadian BCM.

 

A faster and cheaper option is a BCM replacement in my opinion ,it has been done before . What are the tools you use for CAN sniffing ?

 

Hardest part is when you need to access can lines not available through OBD2 port but diagnostic packets with techstream is done through OBD2. This is the tool you would need:

https://www.8devices.com/products/usb2can

And of course a linux computer with the canutils package installed: https://github.com/linux-can/can-utils
So you plug the splitter first in the OBD2 port, then the usb2can and the techstream cable in the splitter (usb2can usb end goes into the linux computer). You connect to the can interface on linux through a terminal (baud rate for most toyota/lexus for this can line is 115200 if I recall correctly) then connect techstream. Just before doing the configuration change with techstream you start listening and dumping the can packets on a file with linux then you apply the configuration change in techstream. Right after the change is done you stop listening the traffic on the linux computer and you are left with a file with all the traffic information. A more sophisticated way would be to isolate the exact can ID for the DRL change from the other noise in the line but there is probably very few people who might be able to do that on this forums so I would be happy just trying to replay the whole dump and hope the right instructions get passed through despite the other garbage. Done it for other scenario and it actually work pretty well, despite having obviously some risks (not sniffing packet but replaying the dump on a different car).

 

On my 2010 there is a option to turn off DRLs in the infotainment.