Join Date: May 2015
Location: Marietta, GA
Year/Make/Model: 2010 Kawasaki Voyager
The fan switch and the water temperature sensor (wts for short) are two different devices. Most bikes have both, some only have the wts and rely totally on the wts measured temp to control the fan. I think your bike has both, but I'm not sure. The fan switch is a thermomechanical switch that closes when the temperature where it is attached to the radiator goes above a certain point. This turns on the fan. The wts changes resistance based on coolant temperature and is located somewhere along the flow path from the engine to the radiator, usually pretty close to the engine. The change in resistance changes the voltage of that circuit read by the ECU. The coolant temp is directly related to the voltage.
A bad wts can cause the temp light to come on at normal operating temps. A bad fan switch can cause the fan to not come on at a low enough temp.
Based on what you describe, I suspect either a bad wts, or maybe a bad fan switch. Most likely the wts. Of course, you could actually have a cooling system problem, too, like a bad water pump or some other issue. Even if it is the wts, don't assume that you won't do damage if you continue to ride without fixing the problem. If the ECU thinks the temps are too high, it may adjust the fuel and timing to compensate for a lean condition that does not exist.
If you are going to try to diagnose this yourself, I strongly recommend that you get a copy of the service manual. The fan switch and wts tests are not that hard, but the specs are bike dependent as is the way you test the voltage of wts circuit.
RAM mount for TomTom Rider 400 (with anti theft module)
6000k LED Headlight & Spots; Kisan Headlight Modulator (works with LEDs),
__Brake Light Modulator, LED License Plate Holder
Dobeck EJK 3.0
Lucky Mirror Extenders
Misc. RAM Mounts for Cup Holder, SPOT, Phone, etc.
Chuckster BAK, Trailer Hitch and Cooler Rack
Wiring for Trailer
Ray's Throttle Mod
Things to do:
Drilling Baffle Plates (Maybe)
Paint HF Tag Along Trailer to Match Bike