Tacho Twingo Bj:99 jumps to zero

Hello together, have a problem with our Twingo. I’ve already found some topics but somehow some topics are not dealt with further or there are other problems. Our Twingo year 4/1999 1.2 58 HP has the problem that the speedometer jumped to zero. After a little search in forums often came the white that in such cases the speedometer should be defective. Have bought a new one at Ebay, but the problem is still there. Now actually comes the funny part of the request…. You can put almost the clock afterwards. After about 5 minutes it shows no more speed and there are 0 km/h … If we park somewhere …. at the shopping or elsewhere, and then re board the speedometer goes again, but nacg about 5 minutes again the same problem ! Is there somehow a relay for what could possibly be defective ? How is the process of this data coming from the dealer ? go over the ECU ?? Are unfortunately a little desperate and hope on help. Lg