2002 Grizzly 660 Manual fan switch?

As long as you do not forget to turn the fan on, it'll only do good for you....except wear the fan motor out faster.
In my opinion, fix the thermo switch circuit and have it working properly. Keep the switch as a backup.

As long as you don't forget to turn it off was my problem. I had an older kawasaki that the fan and thermo switch were giving me problems. After the 3rd time overheating on the trail I put in the manual switch. Once I had the fan issue figured out I still left it. It gave me peace of mind hearing the fan run before I left pavement and also helped with no start trouble shooting. If the fan wouldn't turn on then it was a bad battery or main fuse. If it did turn on then I knew the problem was either in the NSS or the key ignition. I finally fixed all the issues on that kawasaki by selling it lol.

dezz said:

As long as you do not forget to turn the fan on, it'll only do good for you....except wear the fan motor out faster.
In my opinion, fix the thermo switch circuit and have it working properly. Keep the switch as a backup.

Click to expand...

I will definitely look into fixing and keeping the switch as a backup. I just got my Grizz a few weeks ago and I will be doing a whole bunch of maintenance on it and bringing things back up to specs, just not all in the same day. :wink2:


Thanks for the feedback!

If you can verify the thermo switch works. They might of disconnected it for a reason. Depending how they wired it, it should be easy to switch back and forth

Maybe they wired the switch wrong and disabled/bypassed the thermostatic control?
When I installed my manual fan switch, I made sure it would still turn on normally when hot, by looking at the wiring schematic.

JRH_Griz660_02 said:

Maybe they wired the switch wrong and disabled/bypassed the thermostatic control?
When I installed my manual fan switch, I made sure it would still turn on normally when hot, by looking at the wiring schematic.

Click to expand...

I'll look into that. Thanks for the tip! I haven't worked on it in a while. It got cold quick and my garage is only heated by a wood stove. I'll have to wait till the temperature is above -15c or else it takes way too long to warm up.

It's been a while but I'm finally back to taking care of this issue.

How would I go about verifying that the thermo switch actually works?

I would also like to know how to verify that the temp light on the meter works.

Note that I am taking about the thermo switch next to the thermostat.

Well, just to sort of give closure to this thread.... Since the temp warning light thermo switch was surely the original that came with the Grizzly, I just went ahead and replaced it. Quite expensive for such a small part but now I have peace of mind. I also replaced the thermostat.

I now realize that when I tested the old switch with a heat gun, I more than likely didn't ground it correctly. I should have grounded it on the threads and not the lead. It might still be functional so I'll keep it as a spare just in case.

Now the cooling system works as it should, plus I have the manual switch for the radiator fan in case that thermo switch fails.

I've always found the overheat switch finicky to test. You can place the tip in heated water with a ground wire placed on the threads. The tip of this sensor is the sensor part of it. The body is the grounding source.

Inside those thermo switches is usually little thin metal discs or plates. When this metal disc or plate reaches a certain temperature, it flexes and either opens or closes a circuit, depending on the intended application.
I am working on a Rhino 660 right at this present moment with an indication issue of the overheat light. We have tried 2 sensors (one aftermarket and one OEM), but the light is still not working properly. I am now suspecting a damaged wire issue in the harness.

dezz said:

I've always found the overheat switch finicky to test. You can place the tip in heated water with a ground wire placed on the threads. The tip of this sensor is the sensor part of it. The body is the grounding source.

Click to expand...

Thanks for the reply dezz. Apparently that switch toggles at 220f. I had tried placing the tip in boiling water but the water doesn't stay that hot long enough for the switch to reach 220f. Note that I tried testing it while plugged in, trying to make the warning light come on. That's why I tried the heat gun afterwards but it was not grounded correctly. I might re-test the old switch tonight.

Have to be careful though... The heat gun on the high setting can reach 400f or more. Surely too hot for the switch to handle.

I re-tested the old switch and nothing. It did not make the warning light come on. I think it's defective. I'm not going to test the new one because I don't want to damage it with too much heat. I'll just trust that the new OEM thermo switch works.

Would it be too much of a risk if I unplugged the fan and ran the engine till the light comes on? What would be the signs of an overheating engine besides the warning light? Heat, of course, but maybe backfiring?

The only indication you'll get is heat.
Test the light operation by grounding or un-grounding the wire. If the light comes on or not, the switch will not be the issue. Other than that, trust the new switch works. Do not put engine in an overheating condition if you don't need to.

dezz said:

The only indication you'll get is heat.
Test the light operation by grounding or un-grounding the wire. If the light comes on or not, the switch will not be the issue. Other than that, trust the new switch works. Do not put engine in an overheating condition if you don't need to.

Click to expand...

When I unconnect the wire, the light comes on. So, I will trust that the switch works.

Thanks again dezz.