Onan fault 45 'Speed Sense Lost'
I have a 4KVA Onan genset which I've only owned for about a year which has caused me a few issues. It came with my vessel and when I purchased it, it had 219hrs accumulated after 9 years. Generally, other than fixing up the raw water pump after years of minimal use, it runs really well (usually).
I've had to replace the starter due to a water leak from the heat exchanger which caused it to corrode out. I also replaced the heat exchanger too. What originally alerted me to the starter issues was it was engaging whilst the engine was running almost as if there was a short. We figured that was due to all the raw water ingress and since replacing the starter and heat exchanger, it has been running perfectly for the past 400 odd hours
That was until last Friday when that weird starter engaging noise began again. Given this is a new starter and there are no signs of raw water ingress, I began wondering if perhaps the short that I thought was in the old starter may in fact be further up the line in the wiring and may even by in the controller. When I turned the genset off, I was able to trigger the short by tapping the engine with my hand. It wasn't enough to actually start it but enough to kick the starter momentarily.
I decided to leave it for the evening and do some research online. The following morning I went to start it as normal and as it started it stopped and threw the error code 45. The engine itself looks in perfect condition and when running, it purrs along beautifully.
After some further research I replaced the brushes and cleaned the slip rings but the error keeps happening. I was wondering what other options may be worth considering from the braintrust. I wonder if all along there is an issue with the controller which is the source of both problems I've experienced. Seems very coincidental this error occurs the morning after the starter motor began shorting again.
I've contacted a local Onan service tech but I still like trying to problem solve as best I can independently as it helps me learn my systems.