I have an issue whereby my Aux fan comes on as soon as the engine is warm.

 

I have tried a new coolant temp sensor as well as a brand new coolant temp sensor connector.

 

I have also checked my main fan and this is working fine and has only had a new clutch fan fitted a few months ago.

 

The temp gauge on the dash is reading normal, so it is not overheating.... Just seems like the ECU thinks it is?

 

Is there anything else I can check?

Edited June 22, 20196 yr by Peage

Okay so one thing I have done recently is swapped out the ECU. I noticed when I did this there were a bunch of things wrapped in electrical tape on the harness so I wonder if I have disturbed something that might be causing this.

 

I have just unwrapped the tape and found the mess in the pictures below. Can anyone advise the best way to tidy this up? I know there was an alarm installed in the car but this is is now not in operation, so perhaps these are from that install? I have no interest or need to feed power to anything outside of the OEM harness, I have no active alarm or audio amp or anything like that.

 

I was thinking id just remove the non-oem looking cables from those big joins of all the black wires and redo the splice neatly?

 

Put your ‘other’ Ecu back on and my guess is your issue will go away.

Is the ecu currently fitted chipped, is that the reason for the swap out ?

 

 

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I had this problem with the old ECU briefly before I swapped it too.

 

I am having a new loom fitted now anyway, so mods can go ahead and close this.

Before closing the thread - I have two comments....

 

I guess you already know there are two coolant temp sensors; one for the gauge and one for the ECU...:wink:

 

And secondly, the aux fan, as I understand it (someone will correct me if I'm wrong) is also for the benefit of the AC. Whilst it will come on if the coolant gets hot, it does keep the AC gas cool. Does the fan switch off, when you turn off the AC?