Wiring thermo`s

[Zuffen]

Nemesis,

I didn't use the Toyota sender, except for my temp gauge.

I used the thermocouple supplied by Jaycar.

I have it slid under the end of the top radiator hose so it can sense the temp through the wall of the fitting the hose is on.

I set it off the car to an approximate setting then fine tuned it on the car before sealing it in it's box.

It could do with a slight increase in turn on temp but next time the motor is out I'll look at it.

By putting it under the end of the hose I kept it out of the coolant as the coolant will cause a short circuit. The thermocouple can't be immersed in the coolant.

 

[-Nemesis-]

Hmm ok, so the thermocouple reads the temperature off the metal? Sounds simple enough, I assume you lengthened the cables somewhat or did you mount the box near the radiator?

 

[Muzza_NZ]

Nemesis,
the sensor is a thermistor (resistance varies with temp) and not a thermocouple (emf output varies with temp) , so there would be no problem with dissimilar metals (as in the lengthened cables) affecting the output. Big thing to watch as Zuffen says, is to make sure that you don't accidentally ground the sensor

Muzz

 

[svpmx83]

thermo switching can be very good , consider this - wiring fans in series slows them to 1/2 speed then switching them to parralell gives them full speed. i usually ran the fans at the slower speed with the engine running then use the thermo switch to kick them into full speed if the engine heats up. a trick learned from most japanese manufactures.the fans will last longer they keep engine compartment temps lower, you can use the computer or external thermo switch to do this.

This is how ford australia does it for the AU on falcons

37 Yellow should be a fused battery positive feed
Ground EDF pin 17
and run EDF pin 42 through a Tridon thermo fan switch (TF139 is 16mm metric thead and switches at 85/90 degrees) or you could connect this trigger line to the jaycar kits if they can do ground switching

Ignition on will run both fans at half speed
when the thermo switch cuts in they both go to full speed until the temp drops again

I drilled and threaded an 18mm metric sump plug to suit the 16mm thermo switch and put it in the bleed fitting on the thermostat housing