Thermo switch on the radiator bottom tank (JDM ST165)

[sergei]

I am in process of wiring in the link, and untangling loom that ended up in the rubbish bag at some stage.
Car is ST165.
I am removing all A/C related wires in process.
One of the WTF that I stumbled upon is this thermoswitch.

There is normal thermoswitch that is on the top elbow with all other temp sensors. It is normally closed. It is wired straight forward (goes to a A/C pressure switch and then to the radiator fan relay, which pulls it down and opens the radiator fan circuit).
Now this second thermoswitch is a bit odd.
First of all it is normally open. which means it cannot trigger radiator fan relay.
Second one of the pins on it is grounded (which means it was never wired in series with other thermoswitch on elbow).
Third the wire disappears in the under dash loom somewhere nowhere to be found.

I have various wiring diagrams of export ST16X-ST18X (including GT-fours) and I can't find the wire colours or mention of this switch on those diagrams. Closest I could find is the Water Temperature Sensor for A/C.

Now, I think the best approach is to simplify this and not use that switch at all (since it was never for Radiator Fan).

Please let me know if I am wrong about this switch.

[cat007]

Maybe it's for cold start/running and tells the ecu to 'pull the choke'?

What temp does it close at?

[sergei]

Maybe it's for cold start/running and tells the ecu to 'pull the choke'?

What temp does it close at?

Haven't tested the temperature...
It is not part of ECU wiring, neither it is part of cold start injector wiring.
It goes into under dash loom, so I would assume it is for A/C related functions. I haven't included it in the wiring at the end.

[allencr]

...not use that switch at all (since it was never for Radiator Fan).

When coolant exiting the rad. isn't cool enough, assumed to be from lack of air flow by the factory engineers, that switch turns on a fan.
Coolant exiting the head is always hot and would never be used to control a fan.

[sergei]

...not use that switch at all (since it was never for Radiator Fan).

When coolant exiting the rad. isn't cool enough, assumed to be from lack of air flow by the factory engineers, that switch turns on a fan.
Coolant exiting the head is always hot and would never be used to control a fan.

Not true.
Most toyotas operate their fan from the exit elbow.
Eg 4AGE/FE does not have thermoswitch on radiator.

After doing some extensive investigation, that thermoswitch was not even part of the radiator fan circuit. It appears as it is part of A/C system.