Disco 4 (LR4) Lr4 Engine fan runs all the time.

Hello! Cheers from Norway! Have an issue with my LR4 TDV6 3.0. The fan runs all the time. It sound like a plane taking off. Any engine speed above 3000 RPM and the blade would bend quite a bit and somewhat start hitting the engine. I have installed a new fan hoping it would fix it, but no. Further on I have checked the wires from the fan connector all the way to the engine controller behind the battery with the help of schematics and a multimeter. The wires are fully ok and not physically damaged (at least where I can see them). The Gap tool shows no faults. Any suggestions would be appreciated. Thank you

Check the reading from the refrigerant pressure sensor, engine oil temperature sensor and transmission temperature sensor using diagnostics. one will be in fault condition or showing an incorrect reading causing the ECM to run the engine cooling fan at max. duty cycle.

Graculus said:

Check the reading from the refrigerant pressure sensor, engine oil temperature sensor and transmission temperature sensor using diagnostics. one will be in fault condition or showing an incorrect reading causing the ECM to run the engine cooling fan at max. duty cycle.

Click to expand...

Thanks you so much for answering. Can you tell if any of this can be done with the Gap tool?

I would imagine so, I don't use one but the engine & transmission temperature values can be read with a basic reader so I'd think a Gap should be able to read all three.

Also, check with a cold engine, that will make any erroneous reading immediately obvious.

Makes sense I will post the results.

This is right after startup cold engine. No refrigerant pressure sensor found in the live values library I'm afraid:


This is a few minutes later. I gave it around 1500rpm and the fan pwm immidiatly dropped to 0%. I drove away and it stayed at 0%:


After about 10min driving:


I then had a brief stop for around 10min. After starting the engine again the fan pwm jumped to 36% for a few seconds before it setteled at 0%.

It seems to me that the sensors are showing the correct values. Not sure about the fan output and if it makes any difference. I certainly cannot notice any.

Are you able to measure the refrigerant pressure value in the ATCM? Those temperatures and fan behaviour are as expected - the fan has to hit >90% lockup on each ignition cycle to 'prove' it can cool the power train, otherwise a DTC is set. Once it has done that, it stays at 0% commanded lockup (but still rotates due to coupling drag) until needed.
There is also a value for fan speed, I've seen the sensors fault to the point where it registers 1700rpm with the engine at standstill! If you can find the value, have a quick look to make sure its plausible at off, idle & 2500 rpm

Off - Idle - 2500rpm. Temperatures are stable so I did not include them in this chart. As for the refrigerant sensor it's this one only that can match your description.


And this report came with the new fan. As I can understand the only thing that makes it spin before 60% PWM is the coupling drag. Regarding the engine rpm on this sheet it's probably a direct input on the fan's axle. But on the TDV6 the fan is mounted on it's own pulley on the aux belt with a smaller diameter than the one on the crank so it's a bit misleading I guess.

So is everything behaving now?
The PID for the refrigerant pressure sensor is 995A, it may be worth seeing if Gap can add it in.

No. Nothing has changed. I haven't done anything but collecting data. The blades are still bending towards the engine at engine speed 3000 rpm. I am certain it spins way too fast and that can be confirmed by the sound of it.
I will question the manufacturer for the max rpm the fan is designed for and compared it to the fan sensor rpm reading at engine speed 3000 rpm. If the numbers work out it's tachotime.
One thing to remember here is that the old original fan had the exact same behaviour and got damaged when hitting the engine.

Will check 995A

I've just noticed you have refrigerant system pressure of 463kPa at the bottom of your graph screenshot- which is in the expected range - maybe even a little low but it depends upon the ambient temperature. Apologies for not spotting it before, I was viewing it on my phone!.
The only other thing that could account for it is the PWM signal is shorted to +ve and therefore driving the fan at 100% regardless of the control signal - but - that should give a DTC for 'short to positive'. It does sound like the fan is being driven beyond it's limits, can you connect a voltmeter to the PWM connection at the fan end by backpinning, ideally using a meter with a 'duty cycle' range, but if not, AC volts if it's a true RMS meter (of course, a 'scope would be the gold standard!)
I'm curious to see if the PWM is actually that, if you've done wiring checks and included mutual short checks, then it could be a defective control module...

Had my water pump fail today so removal of the fan was mandatory. So I went on soldering some test leads on it. Won't be able to measure anything before everything is back togheter though (of course)

And my Fluke has Trms. Any suggestions on how to connect the wires and which settings to use for the measurements?
Wire No. 1 is permanent 12v .
Wire No. 2 is Gnd.