Me Again, With A Cooling Fan That Won't Switch Off!

[kedw200]

hi again,

My original post got deleted in the data loss problem that I believe the site suffered a couple of days ago. In a nutshell, my wife's Yaris 1.0 (1999 reg) has a cooling fan that will come on after around 3 minutes of driving, then stays on. The blue 'engine cold' light goes off at the usual time of around 3 minutes too- it seems that as soon as that goes off the fan usually comes on (though sometimes there are some exceptions to this rule!).

I have had a mechanic friend look at it and he said to try a new coolant temperature sensor. However, they seem impossible to find(from both local car spares shops, Toyota parts dealer, eBay, etc). Althouthe Toyota main dealer did quote over £50 for one!!

Geoff Peace on here recommended (before my post got deleted!) checking/changing the radiator fan switch by the thermostat. This may sound daft, but where is the thermostat on my engine?

Any help would be appreciated, this problem is really starting to do my head in and I just want it sorted!!

PK

[Geoff Peace]

First remove the air cleaner inlet duct, runs from the front of the car to the air cleaner, this will improve access. The thermostat is at the gearbox or passenger end of the engine. Stand by the passenger side front wheel and you should see a large hose from the radiator which connects to a dome like metal cover on the end of the engine, this is the thermostat cover. The switch is screwed into this cover in the 2 o'clock position and pointing toward the windscreen. Press the locking tab on the connector and pull it off the switch. The fan will stop. You now need to test the switch terminals with a multimeter to check they are open when the engine is cold and closed when it is hot. If the switch is permanently closed, the fan will run all the time. If this is the case then said switch needs replacing. Hope this helps.

Regards Geoff Peace.

[kedw200]

Hi Geoff, thanks for your reply. I found the switch today but unfortunately have no access to a multimeter to test it at present. The fan does not always come on though- today is behaved very bizarrely and kept switching on and off randomly (off for a couple of mins, then on for around 10, etc). Never done that before, usually just comes on after 3 min and stays on!

Might I add, some people have mentioned it could be the coolant temperature sensor? However, I have not been able to find one suitable for this year of car anywhere on the Internet! Just wondered if anyone knows of a good place to get one? It seems only possible to get it for post-2006 Yaris 1.0s! I phoned main dealer and they quoted a ridiculous £50, even more ridiculous when the sensors for other engines seem to be only £15-£20 on eBay!

Cheers,

PK

[Geoff Peace]

The behaviour of the switch is about par for the course. Sometimes it behaves itself sometimes not. I would strongly advise buying the genuine sensor from Toyota. They will match the part to your VIN number. I have seen a good many sensors of this type bought on eBay, they are simply not worth the money you have no assurance it is the particular one for your car which then causes more problems. I know of many sensors bought cheaply, only to last a few months and then having to be replaced by the genuine article. Your choice but £50 is a reasonable price for a genuine sensor, £15 is very expensive for something which is of dubious quality.

Regards Geoff Peace.

[kedw200]

Hi there,

Just a quick update: took the car to an auto electrics specialist, they said it was something to do with a bypass sensor/switch that is designed to override and put the cooling fan on if any other part in the system fails. They said it did not seem to be the coolant temperature sensor but in fact this bypass switch that had failed- it was thus putting the fan on all the time for no real reason. Changed the part with a genuine Toyota one and it has run smashingly ever since! Cheers for the views and help.

PK

[Geoff Peace]

Glad you got it sorted! The genuine Toyota part is by far the best, If I had a pound for every time someone has bought a cheap part and then had to buy he proper one I would be quite well off. Buy cheap, buy twice!

Regards Geoff Peace.