no crank

[R&D man]

I tried starting my m50 swap but the starter wont turn .
I have a m50 with vanos e34 wiring harness(1995) m2o starter and flywheel 260 trans.The car is a 85 325es..
The power windows do not work as well?
I have two wires going to the starter ..from the altenator and One from the existing M2o starter wire ...should there be a third/
When i turn the key on all the lights are on on the cluster.
I am not sure where to start............

[blackhawkimpact]

I think you're missing a third wire. Two small and one big go to starter. Two go to the alternator. One big one small