coolant temp sensor??

[StangG20]

so i have a problem that just arose today. my fans are not turning on. my question is, which coolant temp sensor turns on the fans? my guess is that the single pole temp sensor is for the gauge and the other plug (similar to the knock sensor plug) is for the fan/ecu.

normally the fan would turn on at 212 degrees and shut off around 199 or so. i have a consult device so i can see the exact temp the ecu is seeing. the reading on the consult device is still reading accurately tho. the fan is simply not turning on anymore. even when i click the a/c on.

i tried swapping both radiator fan relays and i checked the fuse under the hood for the radiator fan. what can my problem be? i was guessing coolant temp sensor, but like i said the ecu is still seeing temps over 212 and the fans arent doing anything. temporarily i have jumped out the relay on the passenger side marked "rad fan 1". this turns on both fans at low speed and ive just been driving it like that and unhooking the jumper when i turn the car off.

any ideas?? sorry for the lengthy post. im a bit baffled. :zoinks: :dead:

[stracyznski]

If either of the temp sensors had died you'd see your dash temp gauge reading wrong, either hot or cold all the time. But if thats ok and the consul is showing the correct temp, then that suggests the sensors are ok. Check all your connected, one might not be fully home. If they're all good, check out the wires...

[StangG20]

a little more info:

95 p10
calum RT ecu
ve engine
de temp sensors

[StangG20]

If either of the temp sensors had died you'd see your dash temp gauge reading wrong, either hot or cold all the time. But if thats ok and the consul is showing the correct temp, then that suggests the sensors are ok. Check all your connected, one might not be fully home. If they're all good, check out the wires...


thanks for your suggestions. im thinking it may have to do with the ecu. anyone else have anything?

[p10det]

what you can do it discnect the relays and turn a/c on or disconect the coolant sensoer and look for the ecu ground to be peresent at the relay terminal where ecu will energize the relay coil. also see if that signall is sent to either relay with coolant sencoer pluged in and reading proper temp.
if the ground is supllyed at these time than ecu is doing it job if not you will have to dicnect ecu and test the wire from relay pin to ecu to see if the wire is bad if it is run a new wire uif it is not than the ecu is at fualt.

if you have any questions are if i have made things confuseing let me know

[daveracer]

The two wire sensor controls the fans and sends a signal to the ECU.

The single wire sensor controls the gauge on your dash.

[daveracer]

If either of the temp sensors had died you'd see your dash temp gauge reading wrong, either hot or cold all the time. But if thats ok and the consul is showing the correct temp, then that suggests the sensors are ok. Check all your connected, one might not be fully home. If they're all good, check out the wires...

Nah, they are totally seperate. If the two wire sensor went bad, you could still see the proper temperature on your gauge cluster.

[daveracer]

Also, if that sensor is the same one as the 200sx SE-R, i have a brand new one i can sell you. I was going to use it in my old motor but i abandoned the project.

[XnotedgeanymoreX]

A bad coolant temp sensor should cause the fans to stay on all the time. Even upon cold startup. It does alot of other things when it goes bad too, but this is the easiest symptom to notice. If they arent coming on i would look into something else that might be the cause, it doesnt sound like a coolant temp sensor to me. Good luck!

[dbamaboy01]

where would the two wire sensor be located because i have searched everywhere and cant even find the pic in the fsm

[devonta10]

My temp gauge flouts up and down the faster I go the lower to cold it go but when I stand still it reads right what is that .

[merlin]

My temp gauge flouts up and down the faster I go the lower to cold it go but when I stand still it reads right what is that .not sure if you're just commenting but the gauge should be steady AFAIK. It floating up and down might indicate a failing thermostat!

[devonta10]

no ran it without one

[thefultonhow]

Without a thermostat? That's your problem then. The coolant is always flowing and it cools your engine down too much when you're moving.

[devonta10]

with or without the needle flouts just like the guy above is having .
I changed the engine once and the problem stil excite

[thefultonhow]

I assume you mean "exists" -- if you put in a JDM motor, I think that the temp sensors on it operate in a different range. That's what I've been told, at least. I'm going to swap the ones from my old engine onto my new engine to fix this problem... one of these days...

[p10det]

i think the jdm guage sencor would be different. and am sure it is. but it really deos not make sence that the ecu sencor would be any different other wise nissan is wasting money doing so. Only becuase no mater f or c conditions time of over all ecu temp to tell ecu should be the same cuase it only works on resistance and ecu sees and sends signall to fan relays and keeps signal till a ciurtane resistance is reached. would not make much sent to run a us and jdm fan control at different resistance right?