Engine temp sensor

Other Hardware Sensors
1

Hi,

I read some posts about engine coolant temp sensors, but most referred to sensors that have 2 wires (or 3), but my engine only has one...

how could I get an arduino to read the sensor resitence?

2

It's going to remain a secret until you tell us the cold resistance and the hot resistance of the sensor.

Paul

3

The 'other wire' of the sensor is ofcourse the metal body of the sensor.
Leo..

4

Your 1 wire sensor grounds to engine.

Just a heads up, you cannot share a sensor that is already connected to a gauge or ecu.

5

You might be able to read the ECU. Do a bit of research into your auto make model and year to find out what info is available on the CAN bus. Using a uController with a built in CAN buss controller, a CAN bus transceiver, a ODBII connector, and some code... You can get a lot more info than engine temp.

I have noticed several Arduino CAN/ODBII projects here and there.

I use the CAN bus to have 2 ESP32's talk to each other, works well. I hope, as the temps warm up, to get out and connect up a project to my auto for info display.

6

Wawa:
The 'other wire' of the sensor is ofcourse the metal body of the sensor.
Leo..

That much I know... My issue is that I cannot use a setup like this one, since my ground is fixed

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I know that I cannot share an sensor with the ECU. It's for an older, carbed Triumph and the sensor was used by a gauge. NO OBD...

Now I'm building a TFT display and I want to integrate engine temp reading

This is my sensor

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7

Did you find the solution to your problem yet izi?

8

not yet

9

izi:
My issue is that I cannot use a setup like this one, since my ground is fixed

Then swap the sensor and the fixed resistor.
Leo..

10

Just turn the circuit around.
Use a fixed pull-up instead of a pull-down resistor. It's anyway commonplace to use a fixed pull-up for such arrangements.

11

What is the resistance between the connection terminal and the body hex at room temperature? With probe in boiling water?

12

JCA79B:
What is the resistance between the connection terminal and the body hex at room temperature? With probe in boiling water?

The OP doesn't want to tell us that. We must guess!

Paul

13

It's not that I don't want to tell is that the engine is not with me at this point... I cannot measure it

wvmarle:
Just turn the circuit around.
Use a fixed pull-up instead of a pull-down resistor. It's anyway commonplace to use a fixed pull-up for such arrangements.

Thanks

14

izi:
It's not that I don't want to tell is that the engine is not with me at this point... I cannot measure it

Thanks

Then you really don't know your "sensor" may just be a bimetal switch that closes when it gets too hot.

Paul

15

Paul_KD7HB:
Then you really don't know your "sensor" may just be a bimetal switch that closes when it gets too hot.

Paul

No ... that's the fan switch. The bike had coolant temp gauge so...