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VT SS 5.0 thermos

AzTuati

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Hi guys few questions about the above car.

I assume they came factory with thermo fans, correct me if im wrong lol.
I just got mine the other day and the fans wont turn off, i have to plug and unplug the wiring harness when i need to use them.
Ive checked the relay and its working fine, ive also replaced the coolant temp sensor located under the throttle body because some douche told me that would fix it, guess what happened? Nothing -.-

So i guess my question is what else should i be troubleshooting to find my problem here? Is the coolant temp sensor also the thermo fans switch or is there another? If so where the #### is it located because i honestly cannot find it. Iver never worked on a 5L before so please help me out here lol
 

AzTuati

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Update: just ####ed with the relays and now the fans wont turn on -.- even when A/C is on...

Will get new set of relays tomorrow and see how it goes... As i said i did check them earlier before replacing the temp sensor, ####s me why its making a difference :/
 

accentstencil

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I was going to suggest the relay but you seemed sure it was good.
 

Cheap6

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The relay failing is a common problem. It is the only thing (other than a BCM or wiring fault) which will cause the fans to stay on with the ignition off.
 

Nut Kracker

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Edited:
For god's sake don't swap them around.
The hight speed relay is 4 pin and the low speed relay is 5 pin.
Also, if you plan on getting new ones, they MUST be genuine or specifically for that purpose.
Generic relays will physically fit, but are wired differently internally.

When the A/C is switched on, the high speed relay is activated and a signal is sent from the ECU to the low speed relay.
This switches the driver's side fan on.

Have a close look at the fans. The passenger side one has bigger blades and is used in conjunction with the other one to cool the engine.
This one does not come on with the A/C.
The driver's side fan is the only one that comes on when the A/C is operating and therefore doesn't need to draw a huge amount of air over the condenser (hence the smaller fan blades), as the other one would, over the radiator.

EDIT: Just to clarify a little better.
When the A/C is switched on, both high and low speed relays are switched on.
The L/S relay receives a signal from the ECU switching it over to the single, driver's side fan.
When engine cooling is required the L/S relay is switched back to operate both fans.

Oh, by the way. If the A/C low speed relay (5 pin) is removed or faulty,
NO fans will turn on. Engine cooling or A/C.
 
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Nut Kracker

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The relay failing is a common problem. It is the only thing (other than a BCM or wiring fault) which will cause the fans to stay on with the ignition off.

The fans are switched from the ECU.
 

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Hi guys few questions about the above car.
I assume they came factory with thermo fans, correct me if im wrong lol.
Yes they come standard.

Is the coolant temp sensor also the thermo fans switch or is there another? If so where the #### is it located because i honestly cannot find it. Iver never worked on a 5L before so please help me out here lol
Yes it switches the fans (among other things) and there is only one temperature sensor.
 

AzTuati

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Lol thanks guys, yeah i did see on the relays when i was testing with a multimeter that they were of a different sort, the problem was the prong inside the relays both high and low were stuck on the coil! A light kick fixed that.

And yeah i ended up sourcing a wiring diagram for the thermos after hours of hunting on the web just to see that theres only one temp sensor in the aussie 5L...

Cheers for the help guys much appreciated, all is in working order now and both fans operate as they should, will still be getting new relays to replace both high and low anyway just to be sure they dont stick again anytime soon.
 

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Good to here you found the problem.
Just remember to get the correct relays as I mentioned above.

A friend of mine replaced one of the relays in his VX (EFI one I think),
with a generic one a while ago now and it absolutely destroyed about 2 feet of an earth wire in the loom.
 

Cheap6

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The fans are switched from the ECU.

WRT engine cooling, the low speed fan is switched by the BCM in response to the CTS signal into the PCM and via the data bus. The high speed fan is switched solely by the PCM and can switch on with or without the BCM switching the low speed. Normally the low speed will be switched by the BCM though. Only the BCM can switch the fans on with the ignition off.

The A/C request (CC) or switch input goes to the BCM which then tells the PCM if it 'wants' the high speed fans on, again via the data bus. There are criteria for switching low or high fan speeds on that depend on VSS, A/C pressure sensor and CTS inputs to determine whether the low speed, high speed or neither of the fans are on.
 
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