Yanmar 2gm buzzer diagnosing

[BravoVita]

I have a yanmar 2gmf that I recently finished a 12 volt project on including the panel as no alarms were previously wired. I have questions about all 3 alarms.

1. Charge lamp: The charge lamp was on the last few times I started the engine. A miltimeter confirmed 12.9 volts and I suspect this is because I keep the batteries full with a battery maintainer. The light recently turned off after running the engine for about 15 minutes and I confirmed 13.4 volts. This is probably something I should watch to better understand what might be going on but if anyone has some perspective it would be welcome.

2: Temp lamp: The temp lamp comes on after about 15 minutes of running the engine and I confirmed some readings with a laser sensor to confirm issues. I recently changed the impeller, coolant and air filter and inspected inside the mixing elbo. I suspect looking at the thermostat might be my next step but I wanted to ask what you guys think about my readings.. (I only let them get as high as they did below before number 3 happened below) 120f @ exchanger, 140f @ head, 161f @ thermostat housing, 120f @ sensor housing on thermostat.

3: L.O. Pressure Lamp: after last running the engine for 20 minutes to see what the temps were reading the L.O. pressure lamp came on and I immediately shut down the engine. I actually don't know what this warning is for, how to diagnose it or if it could have to do with running the temp too high but your thoughts and input is appreciated.

Thanks!

[BravoVita]

Just noticed my temp sensor is white and not green, I believe the wrong sensor may be installed if anyone can confirm my readings.. also.. what is the sensor just below the thermostat mounted just above the alternator mount? Is that for a temp gauge?