I have a 2000 CLK 430 that was originally from Canada. The headlights and taillights are on whenever the ignition is on. Is there a way to turn the lights off?

Not really. they use a different headlight switch assembly then here in the USA.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
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MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
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Can I change the switch assembly with one from a US car?

Yes. not a cheap part though.

__________________
MERCEDES Benz Master Guild Technician (6 TIMES)
ASE Master Technician
Mercedes Benz Star Technician (2 times)
44 years foreign automotive repair
27 Years M.B. Shop foreman (dealer)
MB technical information Specialist (15 years)
190E 2.3 16V ITS SCCA race car (sold)
1986 190E 2.3 16V 2.5 (sold)
Retired Moderator

I have located a CLK 430 in a salvage yard that has a headlight switch.

Is changing the headlight switch a simple "take the old one out and insert the new one", or are there other issues between US and Canadian cars?

Can I tell by the serial number if the salvage car is a US or Canadian car?