Electric 101 Question

[Jason2tpa]

Let's use a thermoswitch as the example circuit. You suspect the high temp alarm is giving a false positive. Could someone detail for me the electrical pathway of this circuit when the engine temp is normal and when high temp is detected.

If need be for this particular example, assume the load wire is BLK/GREY and ground is BLK.

[ausnoelm]

Not exactly sure what you are asking, but, I "think" black/Gray gets grounded via the thermo "switch" activating a light or alarm, and possibly reducing RPM! is that what you're asking?

[99yam40]

I would think it depends on what motor you are talking about.
but in general the switch closes when overheat temp is reached and that grounds the wire causing buzzer and RPM reduction, so it would need to tell the CDI/ECU along with set off the buzzer

[fairdeal]

Let's use a thermoswitch as the example circuit. You suspect the high temp alarm is giving a false positive. Could someone detail for me the electrical pathway of this circuit when the engine temp is normal and when high temp is detected.

The wire on one side is "hot" (from - indirectly - the positive side of the battery)
The other wire is "grounded" - same as the negative side of the battery


Its a "normally open" switch ("NO") so at room temperature -
or any temperature below the designed actuation point -
no current flows through it
also expresses as "there is no continuity through it"

Once its temperature rises to the trigger point, it "closes"
and current flows from the hot side to ground.

Now typically in our 4 stroke EFI engines,
the "hot" side wire comes from the ECU
so when the switch closes and that current flows to ground
the ECU recognizes a specific "input" and reacts accordingly

on my F225TXRD, the thermoswitches have a pink and a black wire
the black goes to ground
the pink comes directly from pin # 37 of the ECU

[boscoe99]

Maybe seeing it graphically might help with the understanding of the system operation;

[Jason2tpa]

Its a "normally open" switch ("NO") so at room temperature - or any temperature below the designed actuation point -
no current flows through it also expresses as "there is no continuity through it"

Once its temperature rises to the trigger point, it "closes" and current flows from the hot side to ground.

Perfect. The description I was hoping to receive. Thks!

[Jason2tpa]

Maybe seeing it graphically might help with the understanding of the system operation;

As usual bossman, your illustrations never disappoint. And yes, visualization tools work the best for my brain. Keep'um coming. Big thanks as always.