aftermarket coolant temp sensors: 1wire vs 2 wire help.

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got a single wire sensor on the left and a dual wire sensor on the right.
Single wire sensor is for an aftermarket temp gauge, dual wire sensor is for an aftermarket fan controller.

Do these generally operate the same? can i just splice the dual wire one into the single wire one Plus a ground?

[jfryjfry]

The single wire sensors typically ground through the body (which is why they don't recommend Teflon tape and why you need to add a ground wire if you are using an adapter that mounts in the middle of a radiator hose.

Those two wire sensors are usually one signal and one ground

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Yeah i've had the single wire sensor installed for a year now for a temp gauge, no teflon tape, and the red wire in the pic is grounded to the body.

Now i'm trying to figure out what my best course of action is to add an electric fan controller, the new sensor is that two wire sensor.

I'd like to run both the fan controller and gauge from a single sensor/sendor if possible.

[jfryjfry]

A lot of temp sending units will vary the resistance to ground as the temp changes, giving you your different gauge readings while fan switches are set to close at a certain temp so the circuit is either open or closed, unlike the variable ground in the gauge units.

Short version: you might not be able to use the same. Besides having two means if one fails you might be able to save the motor before bad things happen.

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it's a variable fan controller, i can set what temp the fans kick in at.

http://www.amazon.com/gp/product/B00OBEOXGS?psc=1&redirect=true&ref_=oh_aui_search_detailpage

I guess i could pull the aluminum adapter and drill and tap a 2nd hole, but that just seems excessive.

[jfryjfry]

Not sure what you're asking then... If you want to wire both to the same, then just do it. It probably won't work, but it could.

It does seem redundant but necessary if the sensors work in different and incompatible manners.

[djsilver]

My memory is that on the S13, the 1-wire sensor went to the dash and the 2-wire sensor went to the ECU. The FSM had the specs for the ohms/degree scale for both. I remember something about extra grounding requirements for ECU signals that this may not be compatible with. If you ground the sensor to the radiator support and run the ECU ground to the kick-panel ground point, you can still have "circulating currents" that interfere.


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[rioredstang]

Single wire thermistor reads to ground. Two wire sensors apply a voltage across sensor and read the voltage differential. The (2) wire sensor in the picture looks like a temperature switch. Coolant temp switches were used to control a relay.