club car charger doesn't activate

[CoolDaddy]

I have a 48 Volt Club Car DS. I replaced all 6 batteries. Cart runs as expected. When I plug the charger in I hear the relay click and amp meter jumps a little but it does not power on the charger. I haven't been able to get access to another charger but have gone thru this one with all the checks and all is good relay, diodes, fuses, wiring continuity and AC input voltage. checked relay by plugging DC cable to cart verifying relay changed from open to close and stayed closed. I ran a 12 guage jumper from battery - to the OBC side black wire of the cart plug and the charger kicked on to 15 amps as expected.
I have also check the fuses on the back of cart plug and the gray wire. Ohmed from the gray wire fuse thru the plug and it had continuity.
Battery Pack Voltage: 49.5
DC Cart Plug: Red/Black = 36.8V, Gray/Black 12.3, Gray/Red 49.0V

I was surprised that the Red/Black at the plug was not 49V. My next check will be the wiring from the plug to OBC and the 4 guage battery - to the OBC.

Any thoughts or suggestions? I'm hoping it's not the OBC.