VS commodore thermo fan not working

[pete001]

Hey I have a series 1 vs v6 and the thermo fan isn't cutting in. I let it idle in my driveway today for about an hour and the temp gauge eventually got up to 3/4 and still no fan. Al-tho it does come on when I turn on the ac. I have so far replaced the low fan relay, eng fan relay and the coolant temp sensor any ideas would be greatly appreciated because I would like to fix this problem before summer for obvious reasons. Thanks.

 

[crackles23]

Does the car overheat?

 

[pete001]

no it doesn't over heat but I am concerned that it might in summer if I don't get it fixed.

 

[crackles23]

yea im lost, is there errors showing? your thermos will kick in and out, are u sure they arent kicking in when you dont realise it, does your temp rise? if not, then the thermos probably have no reason to kick in if its not heating up, ive had the issue with my car even after replacing the thermostat the car heats up then drops down, try taking your hoses off and running a hose to flush your cooling system (radiator etc). could be normal I don't know, even take it to a local mechanics, im sure they wont charge you for advise and a quick looksy.

 

[Brett_jjj]

I had a similar problem with my VS V6 not too long ago,I posted about it on here actually.I tried everything to get the cooling fan working .It should come on when the temperature sensor wiring is removed from the coolant temp sensor while the engine is running.The fan should start up on low speed after about 12 seconds of removing the sensor wiring,then the fan should switch from low to high speed after a further 6 seconds.If the fan does not do this ,there is something wrong with the cooling fan system.If it does do this ,the fan system is working ok.My problem ended up being the ECU had burned out where the ECU connector for the low speed fan joins the PCB inside the ECU.(ECU pin F6 blue connector)It was actually all charred black with a hole burned nearly right through the board.Its a wonder no other systems were effected by it.Nothing was there inside the ECU that could have shorted out ,and no moisture had been in there so maybe its a rare fault in some of these ECU's.Who knows,but if you have tried absolutely everything else to fix the cooling fan,and have had no luck,then it might be worth a look.I ended up just replacing the complete ECU after finding this, and its all fixed,both high and low speeds working again.

 

[pete001]

Thanks brett I will try removing the wire on the coolant temp sensor tomorrow and see what happens. Just one thing is the ecu behind the kick panel on the passenger side?

 

[Brett_jjj]

Yep,sure is.Just remove the kick panel to access it.

 

[QuickVRII95]

Just Test The Thermo Fan With Multi-Meters &/Or Use To Long Pieces Of Wire & Attach It Directly To A Battery (Preferably Not The Cars 12v..
(In Case Of A Short Circuit In The Fan..)
Brown/Red (+) - Black/Blue (-)

The Thermo Fan Should Spin When Powered, If It Obviously Is Still In Working Order...

 

[Immortality]

IF the thermo fan is turning on when the AC is switched on then it would indicate that the thermo fan and associated wiring is fine.

the High speed fan is actually activated through the BCM.

could well be a fault in the ecu as mentioned. you certainly won't be the first person this has happened to.

Best way is to hook the PCM to a laptop and use software like EFI LIVE to check the functions of the various components. you will be able to see engine temp and if the PCM is switching the thermo fan on

 

[pete001]

Ok I just went and did the coolant temp sensor trick and it worked, The fan came on just like brett said it would. So im guessing that the next step is to pull out the computer and check that for signs of charring.