Case 1840 charging issue

[Driscoll1840]

Hi I bought a 2000 1840 skidsteer it’s not charging so I took the alternator to get tested that came back good, my issue now is I’m not getting power to the yellow exciter wire,I tracked it back to the relay, there no breaks in the yellow wire I’m gettig 6.8 volts to the #87 post on the relay just nothing to the yellow, any help would be appreciated Thanks