Marelli "Digiplex" ignition systems are also used in Lancia Thema 16 valvers and Fiat Croma 1600. They are notorious for weak manufacturing: the board inside them ages badly so the copper tracks start peeling and the solderings become brittle and break. The module will have to be opened and all the solderings redone and enhanced to stiffen the tracks. In your case it appears that the timing signal is iffy, you will need to also check the wires themselves, they might have started to corrode and the contact between them would have started to fail. Here you can find the diagram of the system http://italiancarsclub.free.fr/Centre-Documents-Techniques/fiat/Manual%20De%20Reparacion%20Del%20Fiat%20uno/0923-04.PDF
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Marelli "Digiplex" ignition systems are also used in Lancia Thema 16 valvers and Fiat Croma 1600. They are notorious for weak manufacturing: the board inside them ages badly so the copper tracks start peeling and the solderings become brittle and break. The module will have to be opened and all the solderings redone and enhanced to stiffen the tracks.
In your case it appears that the timing signal is iffy, you will need to also check the wires themselves, they might have started to corrode and the contact between them would have started to fail.
Here you can find the diagram of the system
http://italiancarsclub.free.fr/Centre-Documents-Techniques/fiat/Manual%20De%20Reparacion%20Del%20Fiat%20uno/0923-04.PDF