Topic

I asked a Jaguar mechanic about my fans which are sometimes running even though the car is not warm enough. I thought it was a sensor but he said that it was the computer which should be reprogrammed.
Is it correct?

Mikstur wrote: wrote:

.. I thought it was a sensor but he said that it was the computer which should be reprogrammed.

A computer (ECU) will only send out commands based on the inputs it receives. The computer is being told it is too hot and so switching on the fan. The sensor maybe at fault your ECU does not need reprogramming.

I would stay away from this so called 'Jaguar mechanic' if I were you.

When you say cutting in too early. What exactly do you mean?
As Paul says it could be a sensor. Coolant temp sensor.
If the thermostat fails closed, the fans come on a lot because the coolant is not circulating to the radiator.
If the radiator/underfloor coolant pipes are not heating up but the engine gets up to temperature - suspect the thermostat.

I agree with both David A and PQD44, it will be a sensor/ stuck thermostat. and stay away from the Jaguar mechanic !!!!

If the thermostat fails to open I guess I could see it on the temperature gauge and the needle is always just below middle. Are there one or two temperature sensors for the fans infront of the radiator and the one in the engineroom

You will probably not notice a stuck closed thermostat on the gauge.
It just means that the fans come on early/frequently. Possibly you may get steam in traffic.

Next time the fans are running, check the temperature of the underfloor pipes and the radiator. If the thermostat is operating properly at least one of the underfloor pipes will be too hot to touch!
If they are only warm/ mildly hot it is a thermostat problem.

There are two temp sensors on the TF, one is for the temp gauge; the other is for the ecu and it is this one that triggers the fans' operation. The temp sensor that controls the engine bay fan on the MGF is missing on the TF. The ecu temp sensor controls both fans.

problem solved. Have got a new cooling sensor and the fans are working as they should. Have been in England in hot lovely weather and the fans have only been running when and as they should. At Brown and Gammonds I got a new thermostat but the MG garage where I bought the car said that it was a wrong one as this was the old type which is placed under the inletmanifold and my car from dec. 2004 has an uprated one which is placed on the other side of the engine. Is this true?

Yes. They changed to a remote thermostat (PRRT) towards the end. In late 2003/early 2004 I believe.

As my sensor for the cooling fan has stopped working again I have looked up this old thread and David you say that there are two sensors. The gauge works fine but here in the autumn the fans ( both the front and also the rear in the engine bay )have begun running once a while when the engine is not hot and recently when I was in heavy traffic the temperature rose without the fan cutting in. I suspect the sensor to the ecu is not working. Can you tell me where it is situated on the engine and is it different from a F? I have a 2004 TF. Do you know where I can buy one? Does it have a color?
Regards Michael

Try http://www.the-t-bar.com/forum/tooltime/94710-temp-gauge-drops-on-rev for the invo