I think your car is working fine, by design only the DRL comes on & the tail lights do not come on at all,
When you turn on the lights at night, it overrides the DRL circuit & the tail lights will come on

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Peter Chu aka PIKACHU
08 C300 Premium Pkg, MM Pkg, Sport Pkg, Keyless Go
86 300E soon to be E36 with Euro Headlights
400E front & rear brake upgrade
16" CLK wheels with Michelin MXV4 plus Green X