Beware misinformation about testing these sensors!

Out of interest really, and with a view to tapping off the voltage signal to provide an engine temperature indicator or warning (maybe a project next winter), I measured the thermostat sensor resistance:
48,000 ohms (cold) seems a high value I thought, and the internet agreed with me, so did Jag technical :

WARNING: These resistance values are very wrong, Sensor JDE1634 has a cold resistance of 48k (at approx 15C).

It would seem from the resistance reading that I had a faulty sensor, but I had no DTCs or other reason to think it wasn't working properly. Hooking up an obd diagnostic tool I went for a drive and checking the two temperatures and sensor voltages told me they were functioning just fine.

So. In conclusion, if you test the sensors using an ohmmeter the result should be in the region of 40-50kohm cold, reducing to a few kohm when hot.
(That is much higher than conventional sensors which measure about 3k cold. I see it said that many aftermarket sensors are no good; their low value will lead the engine management unit to think a cold engine is hot)


For info, each sensor is connected to a 5v supply via a resistor in the EMU. The EMU measures the resultant voltage across the sensor. It is about 3.5 v when cold and 0.5 v when hot.

Finally, I imagine the technical training was written whilst the new AJ133 engine was still under development and the author didn't know about the new sensor.

Happy Jagging😁

 

No need to tap into anything for coolant temperature?
I use the Torque Pro app and it displays coolant temperature in real time. Very handy! You can also set alarms if desired in TP.
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Agreed: plug in to OBD port and Bluetooth to your phone. You can also see oil temperature.

The analogue sensor wire tap is, at the moment, just an idea to provide a permanent ect monitor, warning or a basic display without needing to set up and display on a phone that often has Waze running anyway or having something plugged into the OBD port full time. If I ever do it I will write in a new post.

My intention with the original post is to inform anyone testing an ect sensor what results are acceptable because all the specification information and AI guidance I found was actually incorrect and if followed would result in changing out a perfectly good sensor. (Potentially replacing it with an incorrect aftermarket sensor).