2004 F115 Temperature Gauge Flash at High RPM (no buzzer, no engine reduction)

[briankruz]

Hello All.
Dealing with a blinking temp light on my round Yama gauge at high rpms. The boat runs as it should with no overheat buzzer which really has me scratching my head. I feel this is a false indicator, but would like to be sure. Waterpump & impeller were just done, thermo was replaced 100 hrs ago. Any thoughts or ideas are welcome..

[briankruz]

Thermo tested OK
Poppet (PCV) clean & unobstructed

[99yam40]

I would be looking for what would cause that light to blink.
apparently it is not overheating if buzzer and RPM reduction is not happening,
unless that system is not hooked up properly and not working.
could the tach be set wrong causing the blinking light?

[briankruz]

I would be looking for what would cause that light to blink.
apparently it is not overheating if buzzer and RPM reduction is not happening,
unless that system is not hooked up properly and not working.
could the tach be set wrong causing the blinking light?

I've had the boat for 6+ years & the tach is original to the boat. I did pull the lanyard clip & try to start to confirm the buzzer works.

[99yam40]

I've had the boat for 6+ years & the tach is original to the boat. I did pull the lanyard clip & try to start to confirm the buzzer works.

when an overheat happens the buzzer sounds, RPM reduction kicks in limiting RPM, and the light should light up steady from what I understand.
so find out what will make the light flash without the other things

[JohnF500]

Same issue on 2013 F150- I have tested thermoswitch, thermosensor, engine is not overheating- will let you know if I figure it out.

[briankruz]

Same issue on 2013 F150- I have tested thermoswitch, thermosensor, engine is not overheating- will let you know if I figure it out.

How difficult is it to test the thermoswitch & thermo sensor. I'm also targeting the oil pressure switch on the f-115 as that alarms sometimes at startup.

[99yam40]

Same issue on 2013 F150- I have tested thermoswitch, thermosensor, engine is not overheating- will let you know if I figure it out.

is your temp light also blinking?

[briankruz]

I bought the YDS cable & software & plan to scan when it arrives later this week.

[JohnF500]

The thermosensor and thermoswitch are easy to test if you have a volt meter with ohm setting.

the thermoswitch On F150 is bolted on the outside cover of the thermostat. Two wires with bullet connectors. Unhook and use a 10 mm to remove.

the thermosensor is under the belt cover and mine is a 19mm - be sure to unclip the 2 wire connector before unbolting or you will twist wires and potentially create a short.
see pic for details on testing

[JohnF500]

Yes- my overheat light blinks just turning key to on- not even started.

[briankruz]

Yes- my overheat light blinks just turning key to on- not even started.

Does it continue to blink after starting? What about your oil pressure light? Any action over there?

I get 2 or 3 blinks from each of them when I turn the key to the "on" position. No constant blinking temp light until I'm accelerating. Once I reduce RPM's the light turns off.

[JohnF500]

When I first turn the key everything lights, then everything turns off/ lights properly (trim/tach/hours). The oil light turns off as appropriate, but the temp
light flashes.
Happens when switch is ‘on’ without engine running and continues once starting. Runs excellent. Is Not overhearing, no alarm, never goes into limp mode (which limits rpm to 2000).

[briankruz]

The thermosensor and thermoswitch are easy to test if you have a volt meter with ohm setting.

the thermoswitch On F150 is bolted on the outside cover of the thermostat. Two wires with bullet connectors. Unhook and use a 10 mm to remove.

the thermosensor is under the belt cover and mine is a 19mm - be sure to unclip the 2 wire connector before unbolting or you will twist wires and potentially create a short.
see pic for details on testing

I've been trying like hell to blow this photo up, but it's just too blurry. Anyway you can post it larger?

[briankruz]

Took it out today for sea trial. Still producing the flashing temp light above 3K RPMS. Boat runs like a champ. I ran hard (5500 rpms) for an extended period of time. Pisser is strong, no alarms, no limp mode.. everything is perfect except for the damn blinking light. Yamaha Diagnostic Software checks out with the exception of SHIFT POSITION SWITCH reporting as irregular when the motor is running. I put it in gear & manually pressed the shift position switch & got the blinking temp light plus an alarm. Feel like I'm just spinning my wheels..