nlan · Nov 10, 2012

Hi all
I've bought a 2001 freelander 1.8 a year ago, done HGF and changed the thermostat.
I've noticed that the cooling fans don't start when coolant temp goes above 90deg, as they should. They will work while the AC is on. They will also work when I disconnect the temp sensor.
Note: I used an OBDII scanner to monitor temperature.

Changed the fan controller with another used one, no change.

Had a look at the schematics, there's two control wires coming to the fan controller. I assume the one of interest is the blue/yellow one, as it comes directly from the main ECU.
I don't have an oscilloscope to measure PWM, but I connected a voltmeter on it, which should show some indication of change in PWM (3%-9% below 90deg, significantly changes up to 90% at 114deg).
It keeps showing 0.18V. When temp sensor is removed, jumps to 1.8V.

Obviously checked the wire for continuity from fan controller to ECU

The above make me think that there is a problem with the ECU, not outputting a correct PWM signal.

Any advice?

Diesel Do · Nov 10, 2012

They don't come on until temp is well over 90!

nlan · Nov 10, 2012

Land Rover's manual says 90deg is the temperature where fans start spinning at low speed (6V to the fans). I tested to 96deg.

Diesel Do · Nov 10, 2012

They should hit max speed at 102 degrees centigrade! I'd let it get hotter and try it. If it goes to safe mode when you disconnect the sensor and it works with the AC it suggests that the wiring is ok. Fan module is ok. And ecu is sending signals! It's bloody hard to get em up to temp at this time of year if you're just running it up stationary to test it!

nlan · Nov 10, 2012

This is what I found:
"The fans come on at minimum speed if the coolant temperature goes above 194°F (90°C), and progressively increase to a maximum speed at a coolant temperature of 216°F (102°C)."

However, I'll take the risk and test it to 102°C.

Nodge68 · Nov 10, 2012

nlan said:
Hi all
I've bought a 2001 freelander 1.8 a year ago, done HGF and changed the thermostat.
I've noticed that the cooling fans don't start when coolant temp goes above 90deg, as they should. They will work while the AC is on. They will also work when I disconnect the temp sensor.
Note: I used an OBDII scanner to monitor temperature.

Changed the fan controller with another used one, no change.

Had a look at the schematics, there's two control wires coming to the fan controller. I assume the one of interest is the blue/yellow one, as it comes directly from the main ECU.
I don't have an oscilloscope to measure PWM, but I connected a voltmeter on it, which should show some indication of change in PWM (3%-9% below 90deg, significantly changes up to 90% at 114deg).
It keeps showing 0.18V. When temp sensor is removed, jumps to 1.8V.

Obviously checked the wire for continuity from fan controller to ECU

The above make me think that there is a problem with the ECU, not outputting a correct PWM signal.

Any advice?

The best way is to use an obd reader to monitor engine temp. You can't reliably use a volt meter to measure a pwm signal ether. Or the temp gauge for that matter!
Are you sure the ecu is suppose to send the pwm signal at 90° C? It seems a bit low to me as the stat will be only just open by that temp. My V6 starts the fans on slow at 106°C progressively making tham run faster until they hit max speed at 112°C.
DD's post makes sense with fans on full at 102°C.

Freelaner · Nov 10, 2012

it takes mine about 3/4 hour on tick over in summer to get the fans to come on, so I wouldn't expect them to come on at all at this time of year.

p.s the system has to be bled correctly for the fans to work.

Nodge68 · Nov 16, 2012

nlan said:
This is what I found:
"The fans come on at minimum speed if the coolant temperature goes above 194°F (90°C), and progressively increase to a maximum speed at a coolant temperature of 216°F (102°C)."

However, I'll take the risk and test it to 102°C.

As long as your cooling system is ok 102° C is not a problem.
You have now given me a idea as to why my HG failed again after 1500 miles!! My fans don't even start running until the engine is at 102° C using the OBD live data, now i'm thinking my fan controller may be goosed. Looks like i'll be tasting that this weekend!!
Does anybody have a wiring diagram for the fans on a V6?

zefrench · Jul 12, 2018

Nodge68 said:
As long as your cooling system is ok 102° C is not a problem.
You have now given me a idea as to why my HG failed again after 1500 miles!! My fans don't even start running until the engine is at 102° C using the OBD live data, now i'm thinking my fan controller may be goosed. Looks like i'll be tasting that this weekend!!
Does anybody have a wiring diagram for the fans on a V6?

Nodge68 I am seeing the same problem with my fans not starting till the coolant temp is around the same (according to ODB reader)

Did you figure what your issue was?

Nodge68 · Jul 12, 2018

zefrench said:
Nodge68 I am seeing the same problem with my fans not starting till the coolant temp is around the same (according to ODB reader)

Did you figure what your issue was?

I had a good look at the fan controller and replaced a couple of MOSFETs in it. I don't think I needed to do anything that drastic, as I found some corrosion on the PWM control wire from the ECU. Once everything was cleaned up, it worked as it's supposed too. It's still working now, some 6 years later.

zefrench · Jul 12, 2018

Nodge68 said:
I had a good look at the fan controller and replaced a couple of MOSFETs in it. I don't think I needed to do anything that drastic, as I found some corrosion on the PWM control wire from the ECU. Once everything was cleaned up, it worked as it's supposed too. It's still working now, some 6 years later.

Do you know if the fan controller is available as a separate part number? I will change the Inline temperature sensor that is the bottom hose first (it appears to be the exact same BMW part so eBay has some very cheap to try) and if that does not work the controller would be next.

Thanks for your replies

Nodge68 · Jul 12, 2018

zefrench said:
Do you know if the fan controller is available as a separate part number? I will change the Inline temperature sensor that is the bottom hose first (it appears to be the exact same BMW part so eBay has some very cheap to try) and if that does not work the controller would be next.

Thanks for your replies

The fan controller is available separately, but it's a dumb unit which simply converts the PWM signal from the engine ECU into power to drive the fans. So you first need to check the fan controller is getting the PWM signal and the main power from the fuse box. I know little of the thermostat sensor as EU spec V6s don't have it.

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