Nissan Repair: KA24E --- thermosat, Coolant temperature senosr, coolant temperature sensor, knee jerk reaction

Question
Hi calvin,

Thansk for previuos answears but now i am still struggling with the overheat(cooling fan not spining) problem.

As i said in previoues question, when I plug the connectors from the Coolant Temperature sensor. the cooling fan start up immediately even when the engine is cold. but will stop immdiately after I put it back even when overheat.

yesterday I replaced this senor and the theromsat as well. But still the same. I beleieve the thermosat is ok as both of top and low hoses are very hot .(the low hose is not as hot as the top hose is but still is very hot)

So I suspect the OEM coolant temperture sensor not good.I checked this senor(after plug out from engine) with OMhmetre. the reading is zero and I check the orignal one the reading also is zero. is this means the sensor bad?   


the Coolant Temperature sensor is A27-000E10(very popular). dO you have any details about it?

and in this KA24E eninge, does the cooling fan require the coolant sensor signal "open".

Thansk for your time in advance


Answer
Hi william -

OK, looks like you are moving on in your diagnosis. We are eliminating the basic stuff first, so that is a good thing.

The sensor is NO (normally open) and should close upon heat to start the fan, so if you are checking the sensor when it is cold, then it is hard to tell. Might want to stick it in hot water and check Ohms again. You say that when you unplug the wire from the sensor the fan goes on? That's pretty interesting.

Knee jerk reaction says just leave it unplugged, but please get back to me with the answer to the questions above?

Thank you
calvin