1983 300td had same problems replaced bulbs I cut the stupid German connectors and spliced the wires together only high beam and running amber lights work fuse is testing good by test light I figured ground was good but I said what the hell took it off and passenger high beam dimmed so I know ground was good not for sure what to do it’s either what this post is saying and if so f that connector it will be American spliced together and wrapped with electrical tape or it’s headlight switch or lever