1998 evinrude 90hp temp problem

[dikani]

So first of a bit of info:

Changed the mechanical thermostats.
Changed the water pump (and tell tale is fine)
New battery.
model E90SLECM

So
recently i get a temp alarm sometimes even when the engine is cold. it could happen randomly.

there are two kinds of temprature sensors or temprature switches as you may call them on on the port side and on on the stbd side.

Tried to measure them i guess on the stbd is only a switch and it makes a shortcircuit when its hot enough.
The one on the port side doesent give any kind of resistance when i measure it and i cant find any info about them online.

is there anybody who actually explain or tell me the resistance it should have and how the wiring works? measured that the one brown wire has 0 resistance to the only wire going into the stbd temp switch. and from there both go into the top of the engine.

Pictures of the two temp sensors:

any good ideas out there?

 

[oldboat1]

not a great source on it and will stand corrected, but believe the port sensor triggers the S.L.O.W. feature, and starboard the alarm. Think I might first check the alarm itself and see if it is shorting out.

 

[Fed]

My manual says the starboard side tan triggers at 203F.
The Port side white/black at 96F and the Port side tan at 203F.
All + or - a little bit.

Are you sure the alarm is for temperature?

 

[dikani]

yeah im sure.


Then i guess the tan cables are in a loop and is the alarm cable.
and the white/black is the quick start function.

then the circuit is closed through earth back through the sensor (when it goes off)


then either the sensor in itself is faulty.
or whatever is sending the signal back from the top of the engine to the gauge is faulty.


its only a switch then.

 

[dikani]

for someone else later i found the wiring diagram:
so im actually not that deep into it and i wonder what the diode is doing as i see that the switches runs through it.

at the moment i only see one possibilty and that is that one of the temp sensors sometimes let the current pass through on wrong tempratures.