ABS lamp always lights up

Hello already that forum searched but not really found something. And indeed today I changed my ZEB because the old was defective and the petrol pump did not drive any more. I bought the used ZEB from Ebay, so far everything well so far, gasoline pump as well as blower of the heater and everything else goes now again, but for that since today the ABS light is lit. The first half hour it went out still when I braked, but now it remains permanently on… how do I set the light? n whether the ZEB is defective, or my ABS has failed ?? PS: I drive Ford Ecort Cabrio BJ 93 , 90 PS For good advice I would be really grateful Greeting Andreas