2000 Optimax 200hp alarm at idle

[Tuneboy]

Hi,
my 3.0 Optimax did some alarm beepings after the last drive. I took it out for a spin, had some WOT runs, drove back to the port at idle in the harbour and when i put it in neutral, ready to dock, the alarm goes off and didnt stop. Strangely when i was in gear at idle nothing happened, only when i took it in neutral the alarm started beeping.
From what ive gathered its the overheat alarm (constant beep with a 1 second interval). Problem is i dont have a temperature gauge. My boat has a gauge installed but its not moving at all, probably not hooked up.

I read that there is a smartgauge but its only available from 2001 onwards.

I wanted to know whats going on with my engine so i had some digging and read that there is a certain temp sensor which got a thuird wire where you can hook up the temp gauge.

Think i found it, standing behind the engine, top right corner close to the starboard thermostat.
Problem was: that wire was connected so something and disappeared into the cablesleeve.
On the starboard side i found some not-connected wires. Can it be that one of those is for the temp gauge?

Also i wanted to know how i can hook up a water pressure gauge. The Optimax has some issues with cooling so a pressure sensor would make sense i guess.


https://i.imgur.com/u74OSXl.jpg


https://i.imgur.com/iOhg0h5.jpg


https://i.imgur.com/E1MaUOQ.jpg


https://i.imgur.com/GG9rnP6.jpg

[25two.stroke]

A beep with any interval is not overheat. Overheat is steady. If it changes when you go in gear it also is not overheat. Its probably tps, shift pos. switch (if you have one) or some other sensor that is failing. I believe constant intermittent beeps like you have is a sensor out of spec. Can't tell from your pics if you can plug a ddt into that engine but I'm pretty sure you can. That should be your next step to determine what is wrong.
Yes you can hook up a water pressure gauge.
Yes you can hook up to the loose tan wires to tap in a temp gauge but you have to trace them with a continuity test to see where they go cause that motor has 3 temp sensors in different locations. You would want to know what temp you are reading (port head, stbd head or compressor)

[Tuneboy]

A beep with any interval is not overheat. Overheat is steady. If it changes when you go in gear it also is not overheat. Its probably tps, shift pos. switch (if you have one) or some other sensor that is failing. I believe constant intermittent beeps like you have is a sensor out of spec. Can't tell from your pics if you can plug a ddt into that engine but I'm pretty sure you can. That should be your next step to determine what is wrong.
Yes you can hook up a water pressure gauge.
Yes you can hook up to the loose tan wires to tap in a temp gauge but you have to trace them with a continuity test to see where they go cause that motor has 3 temp sensors in different locations. You would want to know what temp you are reading (port head, stbd head or compressor)

Hey,
that good to hear that its not an overheating alarm. Sensor out of spec isnt too bad i think. It would make sense if it is the shifter pos switch since the alarm went off exactly at the moment i put it at idle from gear into neutral. How can i determine if i have one?
Where can i get a DDT?

Also i will check the sensors. Which sensor should i wire to the gauge ideally?
Thanks