thermo fan working..but not working!

[nalchlan]

hey guys my thermo fan will not turn on automatically. i have tested both the low and high relays they both show resistance when switched.
ive also bridged the the terminals on the fuse/relay board and had the fan running on high and low.
the only other thing i did was earth out the heat sensor on the thermostat housing the temp gauge goes right up but the fan still does not turn on. does anyone know whats happening?

 

[RX25SE]

The single wire is for the gague only.
The two wire one near it is the CTS for the PCM which controls the fans.
If the CTS is unplugged, as a failsafe, the PCM will turn on the fan (and check engine lamp, log code). This can be used to quickly test the fan.

If you leave it idle for ages, how high does the gague go?

Note: the fan will not turn on (or turn off if its on) above 64kmh.

 

[Brett_jjj]

You can test the cooling fan and its systems by removing the temp sensor wire from the sensor and starting the engine.12 seconds after the engine has been started,the cooling fan should start to rotate on low speed,then after a further 6 seconds,it should switch to high speed.If the cooling fan does this,it and its systems are working fine.If it does this,but doesnt cut in when the cars hot,then replace the temp sensor ..

 

[nalchlan]

so: RX25SE
if i unplug the two wire plug just behind the single wire one and the fan begins to work ill know that whatever sensor that plug goes into is at fault?

 

[RX25SE]

Possibly.

That is the CTS. If it faulty it may log a code (look up how to extract codes).
That sensor tells the PCM the state of engine temp so it can work out how much fuel the engine needs. Turning on the fan is another function done by the PCM (and BCM) based on the signal from that sensor.



Like i said, if you let it idle for ages; how hot does it get according to the gague?
May be a faulty gague, just showing hot.

or

do what Brett_jjj suggested.

 

[nalchlan]

i checked for codes just got 12. im not sure how high it goes on idle. the highest has been a little over half way in traffic in the afternoon. so it still gets a bit of air. im not entirely sure if the gauge is faulty, if its midnight and im just cruising along a long road the car will stay cool, but in traffic it gets warmer. ill run it without the cts plugged in, just incase it hadnt logged a code but is still the cause. and brett_jjj i will also check the temperature sensor tomorrow, thanks both for your help

 

[RX25SE]

Mine gets to half idling in heavy traffic, always has.
Above that, the fan cuts in.

 

[bubby83]

mine's the same gets to half way then cuts in

 

[525Peach]

Hi just for the next person that has the same issue,

I had the same problem, Thermo fans not working, Engine getting hot and still no fans. Even switching the A/C on would not get the fans running even though the air was technically 'working'

I was all ready to get a replacement BCM/keys etc when I swapped the high beam relay over and Hallelujah...fans worked and have been working the last 2 weeks no problems.
I must remember to try the simplest things first.