I have read many of the posts concerning fan control sensor and relay tests.  I am not very familiar with DC electrical systems so I need to ask a question that will sound dumb to many of you but here goes: When checking the resistance of the sensor where do I connect my meter to?  Both leads in the connector or one lead and ground?  Neither of these?

Another question:  How do I check that I have a good ground?

I thought I had found that my sensor was bad so I replaced it and have yet to hear my fan turn on.  We have had a very hot summer here so I'm sure it would have come on at some point.  I have checked that I have power on pin 9 of the relay, Grounded E and the fan ran, temp light came on, Bridged 15 & A2 and fan runs.  I thought I had checked continuity for every wire but will do that again.  I thought I had cleaned the connectors ok but will do that again as well.  I saw in one thread that it could be a bad ground at the sensor.  How is it grounded and how do I check it?

Any other helpful hints are appreciated.  Thank you.

Hi mate
if you go to the Download section and search in "Over Temperature Warning Light Test",
it follows on to explain in detail how to go about checking the Fan Motor, and various things to do of it doesn't work.
I have read where simply attaching wires from an external battery (remember brown wire on the fan connector is earth or negative) and positive to the other side, will get the fan turning, after first removing the connector to the Temperature sensor plug behind the radiator. Very hard and cramped in there if the airbox is still attached.
Someone else will give you a better answer I'm sure.
RT

bkhK75 wrote:When checking the resistance of the sensor where do I connect my meter to?  Both leads in the connector or one lead and ground?  Neither of these?

Between chassis ground and either of the pins in the connector. The thermistors in the unit are joined together and that common connection is connected to the sensor case. Each pin is connected to the remaining end of each thermistor.

bkhK75 wrote:How is it grounded and how do I check it?

It's grounded through the threaded case of the sensor via the radiator stand pipe into which it is mounted. Check for good continuity between the hex nut of the sensor and chassis. It is possible that corrosion in the standpipe will introduce excessive resistance. Remove the sensor to inspect the threads for cleanliness, as you might do for a battery terminal.

A word of warning if you remove that sensor, drain the radiator first.
Don't ask how I know.

bkhK75 wrote:.... When checking the resistance of the sensor where do I connect my meter to?  Both leads in the connector or one lead and ground?  Neither of these?

You need to read the troubleshooting page off the Portal tab. Instructions on how to test the impeadance/temp values of the water temp sensor are about 3/4 way down the page. The measurement is taken from pin#10 of the FICU plug to earth but you need to make sure the sensor is properly grounded first as per robmack's post. Values should be about 2.5KΩ at 20 ̊C and around 200Ω to 300Ω at operating temperature.
Don't put your meter on the FICU pins as this could damage internal electronics.

I use the empirical method:

Start bike.

Let idle.

Wait (it can take a few minutes) for the fan to come on.

If the red light in the cluster comes on before the fan then you have issues. (Most likely a dead fan.)

If the radiator cap blows then you have issues.  K bikes have a radiator cap much like cars that will "blow" before the engine gets hot enough to damage itself.

There's a (possibly) even faster way to see if the fan is going to work. If you've got sufficient bodywork off to get at the temp sensor, squeeze the fan motor cover and pull if off (backwards). Now check the brushes - they're well-known for melting the housings as I found out recently.