I really don't care for daytime running lights; in fact, I believe that most DRL designs are dangerous. As of 2008 there is no law or regulation mandating DRL's in the United States. I found a DRL Killer over on the trailvoy web site, but it seems to be kind of a kludge to me. It disables automatic headlights and creates quad-beam high beams; both are undesirable features for me.
I've studied the wiring diagrams and manuals, and this is what I've learned about how the system works.
In DRL mode, the wire labeled A5 on the body control module constantly going from 0 to 12 volts at a fairly high frequency. This wire controls the HDM 'relay' (not really a relay, but a solid state amplifier) number 46 in the underhood fuse block. This 'relay' then commands the headlights to turn on with the same on-and-off-and-on signal, causing the headlights to be on but at reduced brightness. The best way to kill DRL's is to have your local GM dealer disable them as a condition of sale. GM's official line is they will disable DRL's for police or other government agencies, but not the general public. I suspect that a better DRL elimination solution than the one the trailvoy web site would be to simply install a low-pass filter in this line that goes between the BCM and 'relay' 46 under the hood. Please note: I have not yet implemented this because there is a small risk that the BCM will be damaged. If you should decide to try this, you are doing so at your own risk!
There are also several groups lobbying against DRL's. The National Motorist Association, and The Association of Drivers Against Daytime Running Lights two out of many.
Disclaimer: This article is simply information. How you use this information is up to you. If you get hurt in any way, it's not my fault, or anyone involved in any way with the internet, vendors, manufacturers or sellers or anyone else inhabiting planet Earth or the known universe. Information presented here can not be guaranteed to be reliable.
