No Lima load

Moin, I have a big problem with a friend in his old Deutz F2l612: No Lima wants to load The original DC Lima managed only 2 volts charge current, replaced by a three-phase Lima. This does nothing. Now a brand new three-phase Lima built in. This loads something. However, the charging control glimmers something and gets brighter at higher speeds. All cables checked and everything “flying” wired. Nevertheless no improvement. Since this now The second three-phase Lima is the ni The fault can only lie on the tractor. What else can it be? Battery has about 12 volts only by the many attempts. Greetings