Golf cart starter/generator replacement
 

I friend had replaced the starter/generator on his Yamaha (YRDA) golf cart, but it would start but not charge the battery. I spent some time checking wiring, fuses, switches (all of the usual suspects) and found nothing apparently wrong, THEN I noticed the POLARIZED plug for the generator field had the RED and GREEN Yamaha wires going to the GREEN and RED starter/generator wires, yes the wires were reversed.
I made a temporary jumper that allowed me to swap the wires, and the starter/generator would then actually charge the battery. I cut the original Yamaha wires, installed two spade lug crimp connectors and plugged RED to Green and Green to Red and the golf cart works perfectly.
Now I have no idea if this was a wiring error in the starter/generator or the polarized plug, but with this repair the wires can be reversed again if needed in the future.
The bottom line is it appears reversed polarity on the field winding will cause the generator to not be able to charge that battery.
Hope this helps.

Very strange that those two wires were somehow reversed. Thanks for posting this, it definitely could be useful to know in the future. I own a YDRA model. Do you know which year the golf cart is?

Not sure of the year, I think 2018 or 19. Also, no idea how the wires on the new generator/starter were reversed. The white polarized plug can only be plugged in one way. This was definitely something I did not expect. I am sure the wire reversal was in the new generator/starter, as the original unit worked fine until there was a brush or bearing failure and the owner just replaced the whole unit. I never saw the instructions for the replacement unit, but he did say there were specific connections for clockwise versus counter clockwise rotation, so there may have been a note regarding these wires due to rotation.

Thank you Dave Bassett!!
 

My sincerest thank you for troubleshooting my golf cart today. No question you are an expert problem solver no matter what challenges you face; but more importantly the effect you have on others in the process. Paying it forward as you do is contagious and beneficial to our community. I read our social media pages and threads and especially pause to read your posts suggesting and recommending options for requests for help or advice from others. Your willingness to offer help to others is unparalleled.

Thanks for being you --- an inspiration to others.

The year of my cart that Dave Bassett fixed is a 2012 Yamaha gas. In my contacts, I refer to Dave as the Village Tinkerer.

So if you put the two units side by side they were identical, except the wiring had opposite polarity? Makes me think that the new generator was somehow wired incorrectly if it came with it's own wiring harness.

I believe you are correct, but it was not practical to determine if the internal wiring was wrong or if the wires were inserted into the connector incorrectly. It was also not apparent if the wires on the connector could be removed and reinstalled.