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Wipers and turn signals operate without ignition on

Have a 1979 BMW 528i with lots of miles—have owned it since 1982. Lately the wipers and turns have worked with key out of ignition. Replaced the ignition switch and wires but problem persist if the engine is cold. If engine is warmed up, like after a drive, the wipers and turns will not work with ignition off. Let it cool down and Bingo—they work. Where do I start looking for the source of the problem?

"Where do I start looking for the source of the problem? "

In an electrical diagram of manual for your car.