irregular front lamp outage it works somedays and others it doesn't?

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Model is a 2003 s80 t6 The problem is the drive side zon lamp (main driving lamp only) randomly turns off. I have replaced several lamps, wire brushed the connectors, ever Chicago Volvo mechanic has looked at this but the problem continues. The kick it down the road solution I use while driving when this happens is to switch the lights between daytime running back to the normal position, resulting in all lamps working again. Sometimes for days while other times for a few moments. This happens while its raining or not raining (weather appears to not be a factor). Recent situation, the lamp is on during the day or when the front of the vehicle is facing morning or setting sun; however, if the vehicle is say in a parking garage with no direct sun the lamp does not work and the replace driving lamp indicator comes up on the dashboard LCD. I am guessing this is an electrical short of some type and I am wondering if there is a light sensor that could be replaced but then why just the one lamp and not both. The light issue started around 3 years ago but now its on a daily basis. Any suggestions / course of actions? Thank you mlvickery@gmail.com