RiderSite.com - Motorcycle Forums

So my Falco boiled over during the MOT test - fans didn't kick in, fluid squirting from between the rads.

I've shorted the wires for the thermal switch - nothing.

I've bridged the terminals for the relay - and the fans work.

Everything else is working properly so I'm trying to trace down where the switch side problem is using the wiring diagrams and a multimeter. Any clues?

From wiring diagram

On the Relay pin30 is the fused live in, pin 87 is the live out to the fans, if you are bridging these together then as you say the fans are working and the live and earth to and from the fans are fine.

Pin 86 on the relay should be an ignition switched live, pull the relay and check this is live, preferably with a test light rather than the multimeter. If this is ok re-fit the relay and check the wiring on the remaining pin 86 - this should go thru a thermal switch to earth but if you short this pin to earth (to bypass the switch and wiring) then it should activate the relay.

If you have shorted the thermal switch and the fans didn't work then there may be a fault on the wiring to or from the thermal switch or the relay is faulty.

Wally

I traced the yellow/grey all the way to the connector block behind the clocks, which is where the wire from the thermal switch connects to the same coming from the relay. Reconnected it a few times and voila, conductivity was restored.

Every single terminal on this bike seems corroded these days.