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Coolant Temperature Sensor and Radiator Fan Question

937 Views 17 Replies 5 Participants Last post by  Blackawk
2016 YXZ (with 2017+ gauge cluster with temp readout).

Referring to the temperature sensor located in the thermostat housing.

My radiator fan comes on say 9 times out of 10.

The 10th time, the fan never kicks on at the temperature values it should (factory gauge cluster temp reading) - and will cause temps to climb/overheat if I don't catch it, and hit the fan override switch (the fan turns on and works fine when I toggle the override - so the fan itself isn't the issue).

Put in a new aftermarket fan, and cleaned out the radiator as well.

I understand the coolant temperature sensor sends the temperature value to the ecu for the fan to kick on.. how to tell if this sensor is faulty/going bad? Is it possible the sensor could work fine 9 times out of 10, or would it just not relay a temperate reading to the gauge at all (no temperature numbers/values to display on the gauge), etc?

Only other thing I've come across on the forums that seems plausible is the 'circuit breaker' that's inline with the radiator fan wiring may be faulty/going bad, but similar thinking, would it work 9 times out of 10, or just not work at all?

Are these temperature sensors, and/or circuit breakers often needing to be replaced?

Please share your thoughts/fixes. Thank you!

EDIT: or maybe just a simple relay for the fan?!
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Relay going bad...see fan relay below
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Appreciate the reply @fortrdb. Swapped the fan relay with the hi beam relay.

At idle, actually counting this go around, I got 15 fan cycles, then on the 16th cycle I can hear the relay click, but the fan didn't turn on. Then cycled on the fan override switch to cool it down (I can also hear the OEM relay click when the fan off temp is reached when having to utilize the override switch each time - override setup uses a separate relay). Then got 4 fan cycles, and on the 5th fan didn't turn on again. Needed override switch again. Another 4 fan cycles, and on the 5th didn't turn on again. Override switch again, then only got 2 fan cycles, and no fan on the 3rd - stopped there :). I'm going to gather the relays are alright.. or would you think it makes sense to try a brand new relay first? ~3k miles on the rig.

Since it appears like the coolant temp sensor is supplying the temp values with the OEM relay clicking for fan on/off temps, I guess I am leaning toward the circuit breaker piece.. something stopping the fan from triggering on, even after the relay clicks. Looks like it would be part# 5B4-82180-00-00, and/or 5B4-82560-00-00.

Thoughts? Is there a way to bypass the circuit breaker/thermo switch? Put a wire between the two connectors, if anything, just to test functionality? If the OEM relay is 30amp, maybe can just delete the circuit breaker/thermo switch, and put an inline 30amp fuse or whatnot if it comes down to it, or just connect the two leads, and not use anything at all.

That being said, any idea if item #22 includes item #23, or would need to purchase both? Yamaha makes it seem like item #22 contains item #23, per the part diagram below, but #22 is cheaper.

Item #: 5B4-82180-00-00

Item #: 5B4-82560-00-00
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@fortrdb There is a separate overload in the fan wiring next to the stock fan location. This an in-line circuit breaker. I cut mine out when I went to a spall fan, and must have tossed it. IIRC was a small black "bag" style CB.

This is an "over temp" breaker and is designed to cut out when the circuit goes over temp vs over load.

So, yes, it will cut out after repeated cycles of the fan. It might display the symptom you are talking about.

It is not a "plug-n-pray" component. If it is failing you would need to cut it out of the circuit and splice in a new one.

That said. It can be removed from the circuit without it being an issue if you know your fan is still G2G and not running hot / reduced capacity. I cut mine out so that I could run a higher amp (spall) fan in place of the OEM fan.

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Thanks for the reply @WWARt as well. We must have posted a follow up at the same time (re post #3 above)!

Appears there are butt connectors on the 'circuit breaker', but could be wrong.

So, probably makes sense to just bypass the thing.

I too am running an aftermarket fan, after the stock fan quit with similar symptoms of not turning on/or being locked up from water entry, etc.

Did you just remove it/cut it out, and connect the two exposed leads together?

How much of the machine did you need to take apart to get to the circuit breaker? I can see it through the top hood plastic, so may just be able to finagle it from there.

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When I replaced with the spall fan I cut it out and spliced the wires together. That said, I also replaced with a "slow blow" fuse. AKA a heat activated CB JiC the new fan should jam or overheat.

But in the 2+ years since I replaced the fan I've never had an issue. But.... last year I went with a Weller Racing tune that lowers the fan on point. Since then I've never gone over 201* on the temp gauge.... so there's that.

Ahhhhh, yeah. I swapped fans during a major upgrade. So. Yeah... it looked like this when I swapped it.... sorry.
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Nice teardown!

My temps seem alright (I was/still am a little bit skeptical that the thermostat is opening/closing, and water pump is all working as they should - have to figure out how to test those) - that's what I was thinking at first before realizing the fan wasn't actually turning on. At idle machine doesn't go above 195ish (when the fan is working), the fan does seem to cycle on every couple minutes. I also have ecu flash for the fan to come on 10 degrees cooler.

So, you just connected the slow blow fuse inline between the two leads after cutting out the circuit breaker?

Do you have a link to the fuse you used, or amp rating to look for? Waterproof case?

Any, and all info helps!

Thank you!
Sorry. Thats 3 mods back. I know at some point I documented the fuse values. But thats become OBE since I replaced the entire pipe / exhaust with the Trinity and Weller tune and the OEM fan with the Spall fan. IIRC its now just on a standard OEM CB since the change in cycle times allows enough time for the OEM CB to run without issue.
Ahh, got ya. I am running the aftermarket fan as well with the aluminum shroud, but OEM circuit breaker still apparently acting up. Which part number did you go with for the new circuit breaker?

5B4-82180-00-00 or 5B4-82560-00-00?

Maybe I'll just try and order a new OEM circuit breaker, and then try other fuse stuff from there.

Thanks again. Cheers
Sorry, you'll have to give me a bit to research. Getting late for me. Ill check back in the AM with what I used.

What am I getting if I order 5B4-82180-00-00?

Does anyone have a connection to a knowledgeable Yamaha dealer they can ask? I reached out to a few.

Yamaha makes it seem like item #22 contains item #23, per the part diagram (above post), but #22 is cheaper.

Item #: 5B4-82180-00-00

Item #: 5B4-82560-00-00

I found an image of 5B4-82560-00-00 online which appears to be the actual switch/sensor (attached), but nothing on 5B4-82180-00-00.

Is 5B4-82180-00-00 possibly just that black vinyl bag looking piece perhaps the switch/sensor goes inside (picture attached from Wolverine forum - they use the same parts)?

Thank you in advance for your assistance.
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Chiming in, I also have a after market fan on my 2017, I went with the Maradyne as it had a lower amp draw paired with the Hess fan switch. In speaking with Weller they suggested that I delete the Thermo switch all together and just splice the wires together. On my '17 the switch was on the passenger side front rail after removing the plastic and not in the console. It looked exactly like the one shown though. I checked to make sure was the switch by getting up to temp and allowing to fan to come on automatically, I then disconnected the switch which in conjunction stopped the fan. The Hess switch bypassed it though and I was able to run the fan without it connected which is cool.
Thanks all - was easy once actually looking at the machine :) just wanted to gather info prior to diving in. This is believed to be the culprit, simple fix.

@Fish Guy 101
So you just spliced the two wires together -- no fuse?

I was thinking it may be worth it to have this connection fused in case say something gets stuck in the fan it overheats etc - not put back in the thermofuse, but an in-line 30amp fuse.

OR does the fan have a fuse protecting it in the battery box somewhere already?

Does your fan override setup have a fused power cable?
The override has a fuse, Weller told me to just splice them together
Looks like 30 amp fuse in fusebox for fan, so directly connecting the wires it is.
In my limited understanding the thermo fuse is heat related and not actually a fuse. Looking at the fuse box there is an actual 30amp fuse for the fan as well. I think your covered.
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That said. It can be removed from the circuit without it being an issue if you know your fan is still G2G and not running hot / reduced capacity. I cut mine out so that I could run a higher amp (spall) fan in place of the OEM fan.
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