fan on all the time
 

have a friend with a 2.5 kv6 2001 rover 75 who has an issue with the coolant fan
staying on all the time, even when the car is stopped and the ignition is off.Also reckons the temp gauge does not seem to be working either.Only way to stop the fan is to pull the fuse.
Any ideas?
He thinks it may be the temp sensor thats gone ??

I'd run T-Cut's onboard diagnostics are see what the temperature really is, if no reading or abnormal then yes I'd suspect the coolant sensor.

Have a read here https://the75andztclub.co.uk/forum/s...d.php?t=259242 or search, quite a lot on the topic.

Regards

A failed temperature sensor or connection does indeed activate fan operation irrespective of any logical need. This is a safety measure and the ECU 'assumes' the engine could be overheating during the event. However, this fan operation will stop after ignition off. It may well run on for up to ten minutes after, but it will stop. Continuous running 'forever' is a different issue.

The fan system has a permanent live fead and is switched on the earth side of the motor. Any fault that would cause this to happen will result in the continuous fan operation without the ignition. Examples are a 'stuck-on' relay, a worn through wire short and shorting in the fan circuit connectors behind the LHS wing liner.

From the described circumstances, I'd suspect the lost sensor signal. It's likely the fan running hasn't been left long enough to auto stop after ten minutes. First check is to clean and reset the sensor connector located between the heads.

TC

thanks for info guys,TC, thorough as usual!!
He is wanting to sell the car cheap as is, probably shouldn’t get another one but it is in great condition but a long way (200km) from me so id have to drive it back.Im assuming in that state , fan running and not temp gauge the cooling system would still be working ok ?

Should be ok if the cooling system is as it should be ... risky not being able to monitor the coolant temperature at all.

I bought my V6 December before last, for spares as it overheated, had the demist on to run the fan, outside temperature about minus 12c, still overheated twice on the 20 min journey back to my house.

Regards

Is there a link to the temp diagnostic procedure? I have noticed Bumbles temp gauge is not working, hes been sitting a while and I'm trying to get him up and running for POL.

Press and hold the trip reset until 19 is displayed, release the button.. as soon as you see the word ‘off’ appear, press the button again until you select option 7 this will give you the readout.


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Cheers Trikey

Yes, here it is: https://www.the75andztclub.co.uk/for...ad.php?t=55585


The diagnostic section 19/7 for coolant temperature will display a meaningless value if the sensor signal is absent. The usual fix is to clean up the sensor pins and wiring connector and refit.



TC

Don't assume anything Peter. Ask you friend to activate the instrument pack diagnostics which Vitesse provided in the first reply to your request for help. He will then know whether or not the coolant temperature sensor's signal is valid or not. It's a whole lot easier than the dismantling necessary to access the sensor's in-line connector.

Please report back with the result of this test.

Simon