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.

[pete001]

[QUOTE=pete001;1646554]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.[/QUO


Just pulled the computer out and check for charring or anything abnormal, but it all looked fine and in very good condition. May have to just take it to an auto electrician.

[immortality]

try to get hold of another PCM..... beg/borrow/steal etc

[delcowizzid]

the dash may be reading wrong theres 2 different sensors for the vs dash one shows higher temp than in reality and can make it look like the fans are never going to turn on

[Brett_jjj]

If your cooling fan came on when the temp sensor wiring was removed from the sensor,then the fan system,its wiring ,relays and ECU/PCM are all working ok.It wont be the ECU/PCM causing the problem if the fan comes on during this test.I couldnt get the cooling fan to come on at all when my ECU/PCM burned out,even with the temp sensor wiring removed from the sensor it wouldnt go.Id say its just like delcowizzid said above,some temp gauge senders just read higher than others,a lot of people on here have VS's where the thermo fan comes on at around 3/4 temp or more,with my VS the low fan comes on at about half way on the temp gauge and drops it to around a quarter .I dont think Id like to have the temp gauge reading 3/4 at normal operating temp.I would be worried I wouldnt notice it in time if I got a real overheat situation..Next thing Id be doing is just let the car sit idling and keep a good eye on the temp gauge and let it get to 3/4 or a bit more and then see if the fan comes on.

[pete001]

Ok I just went and tested it again by running the car on idle after about 3/4 of an hour it finnaly got to one notch above half and I couldn't believe it the fan cut in. I still think that that it should cut in a little earlier but it could also be the temp sender sending a faulty reading so I will replace that as well. Now to all you fantastic people out there who offered me great helpful hints to fix this problem especially Brett_jjj THANK YOU. I couldn't have fixed it with out you so cheers.

[QuickVRII95]

I Overlooked The Thermo Fan Turning On When You Use The AC... Yeah, It's The Coolant Temp Sensor... They Normally Differentiate, Depending On Genuine Or After-Market... Always Use Genuine Sensors On Commodores...

[astormsau]

There were 2 gauge temp sensors for the VS, the one fitted to most VS's will mis-represent the engine coolant temperature - it was a hangover from the VR but because mounted in a different location it over-states the engine temp so to speak... Go to Holden and spend $15 on a new guage sender, fit it (sits right next to the ECU coolant temp sensor) and then tell us how you go.

Drew

[pete001]

I just replaced the gauge temp sensor today and the now my temp gauge reads a little higher for some reason. so now in total I have replaced the guage temp sensor and the coolant temp sensor, both the low and high fan relays. and even tho the fan does come on now its not until the temp gets to 3/4 and to me that's a bit of a worry so I might have to go replace both of those sensors again with genuine Holden parts. I will repost what happens after I have done that. Fingers crossed.

[astormsau]

I could only recommend using the genuine parts. Holden dealer should know there were 2 models of senders for the VS, one was an early one and one was a later one, you want the later one which reads correctly. I was in the same situation as you, fan would only come on about 3/4 up the gauge... now it comes on at just over half once I replaced the gauge sensor with the revised part.

Drew

[RX25SE]

When you say the fan is comong on is it high or low speed?

The low speed relay is switched on by the BCM first. If the temp continues to rise, the PCM takes over and switches the high speed relay. (maybe someone could post the switching temps, Im on a differnt computer)

Make sure the earth point above the battery is clean. Remove the nut and emery all the earth wires including the body to ensure a good earth.

[b and my vs commy]

my commy has same prob....thanx for this im learnig alot....gonna try this