Help Please. I want to test my cooling fan

I wonder if somebody might be able to help me test my cooling fan. I have removed the three pin ECT sensor plug and I'm hoping I can test if the fan is working by shorting the connectors in the plug. I've checked the fan fuse and it is good. Carrying out this test will also prove that the fan relay is working OK.

I've had a look at the wiring diagram but electrics have never been my forte and I'm worried I might cause damage if I short the wrong pin connectors in the plug.

I can see that there are three wires: 1 x Pink/White. 1 x Green Orange. 1 x Green/Blue.

I'm hoping one of our more teckie/leckie members can confirm which connectors to short to bring the fan on?

Many thanks

You could put a jumper in the fan motor relay between green and black to start the fan. The fan motor receives always-on power down the blue wire from the fuse D, the relay black to green completes the earth path.

Thanks for that Terry. I see what you mean but I've just checked the location of the relay and it looks like the front cover has to come off...phew! I don't fancy going through that procedure. Is there a way of jumping from the ECT sensor plug?

I'm not sure about that. The ECT sensor is a resistance device that is fed voltage from the ECU down the Green/Orange wire and back down the Pink/Whte back to the ECU. I assume shorting those two will cause a low resistance measure and thus cause the ECU to believe the temperature is very high and hence trigger the fan. Probably.

Another alternative would be to jumper the Black/blue wire on the black ECU connector to ground, which should activate the fan motor relay directly (or at least give you an audible click when it activates).

Just let it idle long time----if fan works it should come on. one time over heat should hurt.....if fan does not come on---this saves screwing with wires

Yes Terry, fool the Ecu into thinking that the engine is overheating. Is there a simple way of immitating the resistances shown in the manual without causing any damage? I really don't want to take the ECT sensor out and put it in a glass of hot water!

BTW, John, last week the engine overheated while I was filtering through stationary traffic on the M25. I was concentrating so hard on riding that I didn't notice the gauge was at MAX and the light was on so I pulled over to let the engine cool.

That would have been the time to see if the fan was running but, hey, what can I say, I thought it was all due to an air lock as I had recently replaced the thermostat. (it's happened before). So, yesterday I sat the bike in the garage with the engine running for about 40 minutes. Temp stayed steady on three bars and the fan didn't kick-in at all.

Now I want to imitate the engine overheating directly from the ECT to make sure the relay and the fan are working. A process of elimination you might say.

How about covering half the radiator with a piece of cardboard or such. That ought to get the temps to rise quickly enough.

I want to thank everyone for their input on this. I don't want to risk damaging the electrical system by jumping and shorting. It's a mystery which will require ongoing analysis. I went for a ride today, sat in traffic, did some high speed cruising and then stopped at the supermarket where I let the engine idle for 5 minutes. Nothing. Three bars and no fan running.

I'm going to tackle it in due course, keep an eye on the temp gauge and listen out for the fan. I'll close this thread for now but I'll post any future findings. Maybe it was another air lock after refilling the system recently.

The bike is running fine but if anybody, including me, can figure a way of imitating an engine overheat, it would be fine feather in one's cap. Thanks again

If it's at 3 bars - not overheating - no fan on --- I would just cover the radiator as Tim said and just wait and watch as the bars climb. You have been t max once perhaps that " burped " your system, have you added any to the reservoir after that?

I would just parrot Tim's and "owg's suggestion to cover the radiator and "force" it to go "hot"... that alone should bring the fan on automatically... I know on hot days and long runs I've had the fan come on when pulling in to my garage even with the customary three bars showing on the heat guage... well, there's another two cents you can work with...

Have you checked fan connector or applied power directly to fan to see if it runs, need to start there.
Both fan and low beam relays are the same, interchangeable for trouble shooting, they are fairly cheap and common car part. 4 prong micro relay. In general check/reseat connectors and grounds. Of course fuse "D" and power at this fuse. 

 The ECT sensor does not control the fan relay directly it works thru the ECM, it provides a variable resistance signal as water temp. changes, the ECM uses as reference for fuel injection parameters, the ECM provides a ground to fan relay at correct "Fan On" temp. thru Black/Blue wire. The ECT sensor also send signal to gauge cluster/meter CPU thru separate wire for water temp.

 IOW if the temp gauge is working correctly and the bike runs normal untill it overheats is probably not the ECT sensor, I would not advice jumping the connector at ECT in any case, it could harm the ECM or meter CPU!!

 Both postings by Terry are very good things to try, jumping the "Black/Blue" at the ECM to ground with switch on should start the fan, if relay is good and fan is getting power, is the easiest just remove side cover, wire #16 on black ECM connector.

Good Luck.

BTW have a Box fan Handy or running in front of bike JIC while you are working this issue, no point in taking a chance of overheating engine IMO.

Thanks zrx212. I have a lot to work with here. Do you know if the fan connector plug is easily accessible?

I have removed the whole front cover tupperware before and I don't recall it being a whole lot of fun.

Loosemarbles wrote:

Thanks zrx212. I have a lot to work with here. Do you know if the fan connector plug is easily accessible?

I have removed the whole front cover tupperware before and I don't recall it being a whole lot of fun.

Easily is not the case, but while laying on floor, you can get to the fan connector by removing the LH lower skirt and the radiator cover/grill, possibly as much access as with front fairing/cover off, is a tight area, IAC those would have to come for either case. BTW blue wire +, black -.

TIP/PSA when removing lower skirt fasteners, remove also  the 10mm upper bolt next to phillips head screw where the lower skirt meets upper cover, this will allow you to move skirt back some to unhook front plastic catch without braking it, fortunately learned that lesson with old/damaged parts. 

Useful info, and I see exactly what you mean. I'm gonna give this a go in the coming weeks. Thanks for going to the trouble of a very informative post. I'll take some photos as I go and post my findings for the future use of other members. Remember, every SW will be as old as mine some day!

Loosemarbles wrote:

Useful info, and I see exactly what you mean. I'm gonna give this a go in the coming weeks. Thanks for going to the trouble of a very informative post. I'll take some photos as I go and post my findings for the future use of other members. Remember, every SW will be as old as mine some day!  

 No trouble  at all, yes is good too know of possible failure issues and prevent them