Yamaha Drive Issue with Controller

[peter.tygh]

Hi everyone,
I have a Yamaha G29 that has a derating/surging issue, batteries are at 75% capacity, all the terminals are good, but it has error's codes #27 MCU internal error, plus code #99 Undescribed error, it just repeats.
Notice there isn't much around on the Yammy fault codes full stop, any advise would be appreciated, cheers pete

[cgtech]

Please elaborate on the "batteries are at 75%" thing.

[peter.tygh]

I mean I did a discharge test on the battery pack, got about 70 minute on the 4 x T1275's

[peter.tygh]

Actually took it for a drive this morning, it takes off like a rocket, then goes ok, then it intermittently stutters with pedal down, then away again, then sometimes after bringing cart to a stop, locks up & doesn't move, you can hear the solenoid working, turn the key on & off a couple of times then your off again. I checked foot switch test fine, but comes up with the MCU & unidentified faults, I will collect next week & put on the hoist, will swap throttle pot over to prove is my last idea for now

[cgtech]

Unfortunately, there are many "undescribed errors" even us yamaha dealers arent privy to. They are usually internal faults inside the controller, but not always.

[peter.tygh]

Thanks cgtech,
I might as well put it up in the air, check motor brushes & throttle pot, for the next stage, that will cross most of the boxes off, cheers pete