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How can I test my engine temperature sensor?
Still troubleshooting my urban cooling kit fan
Thanks in advance
Neil

what's the problem?

Just went back through your posts - did you find the little wire? Was it connected into the ECU?

The engine temperature sensor signal on green/blue coloured cable runs to pin 6 on ECU on both early and late versions of M3W. Common signal ground for this and several other sensors is on yellow/black cable running to pin 26 on ECU. So sensor is there and connected to ECU via engine wiring loom even on models without urban cooling kit fitted.

Have you checked through fitting instructions for urban cooling kit Neil assuming your car was pre 2014 model that didn't have it factory fitted, particularly the need to load new calibration file to ECU? Instructions are available for download here as per previous thread.

Thanks for the reply. It’s a 2013 May build. I am the second owner. First owner had the kit installed, including the ecu flash. Says the fan worked. It hasn’t worked for me. I found pin 15 (from the uc kit) was pushed back into the connector and probably not making contact. We fixed that and thought that was it. It wasn’t. The temp sensor goes from 2.5k ohms cold to 25 ohms hot. Seems like that is enough of a difference but I don’t know what those results should be. The speed sensor seems to work because the speedometer works. I can ground terminal 85 on the relay and the fan runs, so everything downstream works. Relay, fuses and the fan itself. I measure the temperature at the sensor at about 250 degrees Fahrenheit with the car sitting still but the eco is not grounding the relay. It’s also not cutting out engine firings as it would before the ecu flash.

Thanks for the sensor wiring info as I will check to make sure there is no brake in the wiring.

Is there readily available software or readers that allow you to see what the ecu is seeing?
Thanks,
Neil

The cooling fan relay triggers from a ground on (black/blue?) cable from ECU pin 15. On pre 2014 models this pin was unused but the sub loom supplied in cooling kit add it, matching later models which had cooling fan ex factory. The firmware flash presumably activates pin 15 and I would blame lack of this upgrade but for the fact you say the cooling kit was working previously. Given cooling fan works when its relay coil contact 85 is grounded this only leaves the sensor and relay trigger wiring plus sensor itself as possible faults. Since you have already had problems with pin 15 ECU connection I would double check that as well.

S & S provided Pro-Tune software to read ECU parameters via a USB socket on your car. Hopefully others current with this software will be along to give instructions, or you can download and read the manual for it here.

Our early 2012 car never had the urban cooling kit. In fan-less form, we only once had a skip-fire incident in a very long start-stop traffic jam on a UK warm summer day. After this, we fitted a manually controlled fan blowing on the back of the engine which we put on if we are in a big jam. Never had a problem since even on hot days in southern France/Spain...

Protune will enable you to see the temperature being read by the ECU.
It is only available for Windows PCs and you will need to install the software drivers that come with the software.
It is likely that your ECU is locked so Protune will read the ECU data but not allow you to make any changes (other than clear any fault codes).

Thanks all for the quick replies!!
I’ll look into the protune software. Ecu being locked is probably a good thing for me!
Best,
Neil

First, many thanks to all who replied, you are life savers!
Looks like the real problem was that pin 15 in the ecu connector wasn’t making contact with the ecu. Once that was resolved, I wasn’t getting the engine temp high enough to turn on the fan. Can’t say enough great things about protune! When the ecu saw 200 % f the fan turned on. My non-contact infrared thermometer was showing 240 %f but the ecu was reading 200%f. So now the system works!!! The only remaining question is whether the thermistor is correct or the non-contact thermometer.
P.s. the protune gauge screen is amazing. You can see so much of what is going on in the engine. I find it better than obdii in some respects.
Again, thanks to all who responded. I hope one day I can return the favor.
Neil