Fan Control Module (again)

[jhock]

I know this has come up time and again, and I have searched the old posts for advice, but most have been resolved by changing the fan control module/assembly. That is not the case for my 2010 XC60. I'm on my fourth brand new module (sometimes the whole fan assembly) and am having the same issue. The fans will not run when the car is hot unless the AC is on (AC tends to kick them into high). The car will get up over 100C and the fans will not turn on. But then the fans will kick into high when turning the car off (even when the coolant is 85C).

I'm pretty sure it isn't something else in the cooling system because it is fine as long as their is air flow over the radiator (unfortunately I live in the city). So it is the fans not coming on when they should, but I'm pulling my hair out as to what it could be (my mechanic can't seem to figure it out either). Fans won't run when they should, run like crazy when they shouldn't. Keeping the AC on tends to keep the car between 89C and 95C.

I've seen a couple of hints that the violet signal wire could be the culprit (either a short or has too much resistance), but I'm not sure what I'm testing for to see if that might be the issue. Would appreciate any advice.

[pgill]

JHOCK,

It does sound like the control wire may be bad (Violet signal wire if you will)

I upgraded my LR2 (single fan) to a Volvo (Dual Fan) for a S80 and it is likely that this fan would be a drop in replacement for your XC60.

With that in mind take a look at the Land Rover board

https://www.freel2.com/forum/topic36668.html

Good luck

Paul

PS it is possible that the ground is bad and that it is affecting the Voltage of the signal. You should back probe the ground wire at the fan module with the fan running. (Measure from there to Battery -) If you get something like 50mV 0.050V then I would ignore it. If you get anything near 1 Volt then fix the ground first. The signal on the Purple wire is only 3 Volts I believe and it will need a good ground reference, if that makes sense to you.

[jhock]

Thanks Paul, I will do that. I have confirmed there is no short within the wiring itself so far, will check the ground.

Is it also possible that the computer just doesn't turn on the fan until 100C? That seems odd to me since it s a 90C thermostat, but the fan finally does come at a low speed at 100C. It isn't like it doesn't work totally, it is just running 10C higher than I would expect it to (my mechanic felt the same).

[pgill]

I'm not sure how the fan controller will interpreter the signal from the ECU if it has a bad ground reference. I believe that the signal is PWM (Pulse width modulated).


One thing you should do for your 3.2 or 3.0T is replace the Thermostat. They fail around the 10 year mark and you are already there. My 2010 S80 failed after 8 years.

https://www.freel2.com/forum/topic32245.html

Good luck

Paul