[dandjonfmk]

I had same problem on same model/year Yamaha cart two years ago. Found it to be the relay solenoid. I measured the voltage drop across the relay coil when problem occurred to be 12 volts but relay did not pick up. I could tap on it with the handle of a screwdriver and the cart would run OK. Ordered one through Amazon ($40) and no problems since. Before I repaired it, it stopped 3 times between Lake Sumter and Charlotte.

[Boffin]

If it turns out to be the ECU, it will have a part number like this: JC0-8591A-02-00 ENGINE CONTROL UNIT ASSY. Cost of part is about $300 - $350.