This Preliminary Information communicates to techniciansthat the Daytime Running Lamps (DRL's) or the auto headlamps will not shut off when using the daytime running lamp disable switch (Which is part of the headlamp switch), if the vehicles was built for Canada (RPO Z49). These vehicles were built with different software that doesn't allow the DRL's or Auto headlamp to be shut off. Canada law prohibits disabling daytime running lamps (DRL's) or auto headlamps.