VS Thermo Fan Fault

[Superjet0701]

Hi to all,

I need some help with the thermo fan on my VS 11 V6 Calais, over the last 3-4 months I have replaced the following, water pump,

thermostat, temp sender, flushed and replaced coolant and bled cooling system correctly, all has been going well untill a few nights

ago when I was sitting in Maccas drive thru i had the high temp alarm beep at me only to realise that the temp had gone through the roof!!!

I pulled over to find that my thermo fan was not working unless I had the air cond turned on, in which then the temp runs normal. So the next day I went and purchased a new

coolant temp sensor and replaced it but the thermo fan is still not working without the air cond turned on.

I have searched all commodore forums for an answer to why this would happen all of the sudden, but none of them have an exact answer to my problem, so anyone that can help

would be greatly appreciated!!!

[VS_Pete_1]

No offence mate, but can you please break your post up into some paragraphs as it makes it a lot easier to read.

Cheers

[social]

VS pete 1,
ive seen u say that in 2 posts now, wats with not being able to read it clearly?

[VS_Pete_1]

Must be just me and I haven`t even had a beer yet.lol

[Superjet0701]

Hope that helps Pete my first post so thanks for the advice, it certainly

makes it a bit easier to read!!!

Thanks Clint

[VS_Pete_1]

And eye sight not what it used too be. lol
Cheers Clint thanks for looking after the old farts.lol

[moff_man]

could be 3 things in my opinion...

1. fuse or realy blown and yes the fan will work with the a/c on but you will not get high speed
2. temp sensor which one did you replace there are 2 one for the temp gauge and one for the ecu (computer)
3. wiring issue from the sensor to ecu or ecu to fan issue or even a ecu issue

i do recall having this issue on a later model car but carnt for the life of me remember what it was, i think it was just a realy.

[Superjet0701]

I have swapped the horn relay with the thermo fan relay, but no difference

I have replaced both temp sensors, Guage and thermo fan sensor

I starting to believe that it is related back to the ECU?? may have to wait

until the local autolec opens back up next week??

Thanks for your advice

[hako]

Have a look at this post:
Thermo fan/sensor/Air con? - electrical fault

It shows a similar problem to yours and a simple way of checking if the fault is in the ECU plus it may save you a costly visit to the auto-elec.

[Superjet0701]

Thanks Hako, I will have a look at it tomorrow and keep you updated with how I go!

[The1]

according to my gregories manual

low speed fan operates though the bcm to the ecu, high speed fan operates only from the ecu.

The high speed fan only comes on if the bcm fails to respond or if the temp sensor returns a temp of higher than 110c or is faulty.

if you disconnect the coolant temperature sensor and start the engine after 12 seconds the low speed fan should come on after another 6 seconds the high speed fan should come on. If this happens the fan circuit if fine. If it doesn't then it's a relay problem.

There is also another possibility the fan relays use a 40amp fuseable link thats in the engine bay and also uses fuse number 10 7.5amp under the steering wheel which is why you might be able to get it working manually but doesn't work automatically.

Hope this help you find out what's going on.

[kopper69]

Nice work The1 and nice work gregorys

[Superjet0701]

Hi The1 and thanks for your help,

I checked the operation of the thermo fan as you described and it works on

both low and high speeds when you disconnect the fan sensor, I have

checked both the inline and under dash fuse and they are ok, but still wont

work automatically, has me puzzled!!!

[The1]

the fan circuit is fine then and it's also working fine with the aircon on so its not fan circuit problem.

Disconnect the coolant temperature sensor and check the harness connector with the ignition on, it should have 5volts. If it doesn't it's either a wiring problem or the ecu.

If that's fine then to test the coolant temp sensor it should have these resistances on it's connector pins at the following temperatures. I just pull it out and put it in cold water with a thermometer and then hot water and measure ruffly both ends of the scale.

-10c 16.320kΩ
0c 9.517kΩ
20c 3.555kΩ
30c 2.268kΩ
40c 1.483kΩ
70c 0.474kΩ
90c 0.244kΩ
100c 0.180kΩ
110c 0.134kΩ