That makes more sense, the old Series Controllers are not very smart and will allow the power to drop off and keep on going
The Solenoid and the cart will not stop working at 46v, the voltage needs to get a lot lower.
Your battery voltages are pretty low depending on how much it had been driven before you checked the voltage so we will need to check the charging as well.
The OBC provided the negative activation for the Solenoid in your system and a weak FET inside the OBC can cause the Solenoid to "chatter".
I would try to verify those first.
Disconnect the pack negative cable and leave it disconnected for more than
10 minutes to reset the OBC.
While the pack negative is disconnected, disconnect the
yellow wire from the Solenoid coil (small tab or post) and run a new wire from that solenoid tab
directly to pack negative.
Connect the pack negative wire back and charge the pack.
After the charging is finished, test drive and see if there are any changes.
Here is your wiring diagram:
