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Thermo Fan Issues

Fat goober

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Only low fan comes on with a/c, not high fan which comes on when dangerous high temp is reached and both are on if a/c is also on. Also low fan is bcm controlled and high fan is ecu/pcm temperature controlled from cts.

Try switching the relays around in bay for fan and taking 1 off at a time and or wire bridging relay sockets between the 2 to test operation.

If you disconnect tps and turn engine on you will get an engine light on dash and low fan will come on in a few secs followed shortly by high fan to see if both fans work.

Changing cts idling you will not see any fans on as you need high temps after driving.

As to your fuel usage perhaps check/test/renew 0xygen sensor as that can make ecu change idle/power/fuel usage
Does that work for both 6 and 8 engines as im not sure if my fans are working, my car doesn't seem to be getting excessively hot, though I can usually tell when they turn on/off but on a drive yesterday I couldn't. Thanks
 

Vin999

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Cant recall exact temps but V6/V8 run different thermo temperatures anywhere from 80's to 104 degrees for fans.
my car doesn't seem to be getting excessively hot,
if your car isn't overheating then there is no problem, turn a/c on and fan will operate
though I can usually tell when they turn on/off
if they turned off means car got hot and they work and/or turned of A/C
but on a drive yesterday I couldn't. Thanks
car didnt get hot enough or your music was tooooooooooo loud or you can't remember hearing them typing post at 4.50am in the morning ;)

Also
 

Fat goober

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Cant recall exact temps but V6/V8 run different thermo temperatures anywhere from 80's to 104 degrees for fans.

if your car isn't overheating then there is no problem, turn a/c on and fan will operate

if they turned off means car got hot and they work and/or turned of A/C

car didnt get hot enough or your music was tooooooooooo loud or you can't remember hearing them typing post at 4.50am in the morning ;)

Also
thanks for reply and yes they are working, l walking dogs at 430
 

Waz888v8

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Hi all need some help on my VX, first of all is the thermo fans ive checked all plugs and relays but only the low speed fan comes with or without the A/C on the high speed fan never comes on ive changed the Coolant Temperature Sensor hasn't done anything i checked and its got power but no earth ive swapped the plugs so now its only the high speed fan that comes on and not the low speed fan im in 2 minds of taking it to an auto electrician or bridging both fans so they both run whenever needed im worried it will be to much for the 1 relay, also noticed that its been using a bit of fuel lately I use 98 only and at half of tank ive only done 140kms if anyone could help or give any advice it will be great thanks.
Change the temp sensor on your engine v6b is next to the thermostat at back of engine v8 right hand side front of engine in the head the sensor in the coolant is to tell if the water level low good luck
 

Representative

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Things sound not quite right and you’re confusing yourself talking about PCM and Mace and swapping fan plugs.

Firstly air con low fan on passenger side is controlled by BCM, High fan on drivers side is controlled by the ECU. The ECU will trigger the high fan when coolant reaches over 100/104C from the CTS reading.

The low fan will only come on with a/c on when driving or idling, if coolant temp hits over 100C then high fan will come on as well and turn off once temp goes below 100C and back on if you don’t move and get cool air thru radiator. So both fans will only be on when a/c on and high temp over 100C from memory it could be 104C. High fan has nothing to do with a/c and BCM

To simply test fans, disconnect coolant temperature sensor, turn on ignition and start engine and let it idle, you will have engine check light on dash, then shortly low fan will come on followed about 15 secs later by the high fan and both fans will be on. The ECU turns fans on to cool engine with the engine warning light due to not receiving temperature reading so thinks engine/coolant has reached boiling stage. Most times even at idle with a/c on and a stinker of a hot day, you will never hear or see the high fan come on unless radiator/coolant is overheating or cactus coolant temp sensor so most people think the high fan doesn’t work.
if doing that test both fans are on while idling with the CTS plug off then they are both ok along with the ECU.

Alright, so just to clarify, I have the same issue I think. I've taken off the sensor and it kicks the driver side fan on low, wait 15 to 30 second and it doesn't kick into high and passenger side does not kick in at all. Do I have a buggered fan relay?
 

Immortality

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Low speed fan comes on at 104°C or with the AC and up to 64km/h vehicle speed. The high speed fan comes on at 108°C.

It sounds like you have the typical fuel gauge sender error although yours sounds quiet extreme. You shouldn't fill the full up to the top of the filler neck. When the tank is full there is still supposed to a little room at the top of the tank for air to allow for expansion with heat.
 

Immortality

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Change the temp sensor on your engine v6b is next to the thermostat at back of engine v8 right hand side front of engine in the head the sensor in the coolant is to tell if the water level low good luck

??

The L67 supercharged engine as the coolant temp sensor under the thermostat at the back of the engine, the regular ecotec V6 has the thermostat at the front of the engine and I do believe the thermostat is located under it too.
 
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