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Discussion Starter · #1 · (Edited)
I have a 93 TRX300 with the optional cooling fan unit. How do I activate the fan?

The oil light would only come on when I tapped the fan control relay. I bought a used one with the same part number but it’s upside down from the original. In the pic the original is the big one and little one is labeled with the part number from the fiche.

Anyway the oil light comes on and fades after a few seconds like it should. The oil sensor ohms out at 14KOhm; so I need a new one. when I ground the sensor lead the light works. You’d think the fan would activate but it doesn’t.

So I’m going to check out the fan motor leads. There’s no wiring diagram in the service manual except probably a purple power lead.

Any other thots? Thanks
 

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I've never worked on an optional 300 fan, so don't take any of this as fact... the purple wire you mentioned is hot whenever the key switch is on (along with the accessory power plug) according to the FSM. The cooling fan kit shows that there should be a sub-wire that connects to the fan motor, but I can't find a wiring diagram for the optional kit so don't know where that lead goes, how long it is, or what it looks like...

On all other early Honda cooling fan equipped ATVs, power for the fan control (fan motor) is supplied through a separate fuse (white wire I think?) in the fuse box. Those early Hondas used a fan control module having 6 leads... whereas the alarm-only equipped 300s have 5 wires. I'm guessing here... but perhaps your 37810-HC5-971 fan control module requires that all 6 wires exist in the connector plug?

@jay10 might know all about this..?
 

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Discussion Starter · #4 ·
Thanks for replies. @fishfiles The diagram shows one wire harness it’s either two or three wires I can’t tell just yet. Have to pull the inner fender shroud. The fan blade will rotate but not freewheel—seems normal.
@retro good idea I will look at the fuses. I am getting accessory power.

You know all that open space around the TRX300 head? Now completely taken up by the fan and ducting. So if a TRX300 never needed cooling without this option, it certainly will now.

Thankfully nothing on the quad looks hacked or chewed on
 

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@retro thank you, i can't be of any help on this issue, as myself and @machinecrook toggle switched our oem honda cooling fans, but I'm tuned in and enjoying the the read fellows!
 
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Hi: I have never seen a purple wire on a Honda ATV -- are you sure? This may help.
 

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Discussion Starter · #7 ·
Sorry it’s Pink
Whatever puts power to the Blue wire coming out of the FCU is what I need to find. Otherwise I will put a manual control on it.

I will look at Mela’s diagram
 

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Hi: here is a dia. with pink wire.
 

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Discussion Starter · #10 ·
Ok I used a waterproof switch and plugged it in to shunt power from the accessory circuit to power the fan. pics show the oil light activating after ignition powered and lonely blue wire which I will label and tape.

found power everywhere except at the blue wire coming out of the FCU powering the fan. I tried timing the high temp condition with no luck, so I don’t know what else to do. Everything works now and I can control the fan. Just need to build a splice to restore power to the accessory circuit.
 

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It’s dark down my shed now but if it helps I can confirm wire colours tomorrow for you? Mines obviously a factory fitted cooling fan, there may be differences, I don’t know?
 

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Discussion Starter · #12 ·
Thanks Sam. No I got it done thanks. This is a factory fan kit too; older than yours so not sure what would be different. My fix didn’t result in any cutting but I will label my changes in case the eventual new owner needs to know.
 

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Ok cool. Well I can confirm the blue wire on a 93-97 loom, just identified my loom as a gen2 not gen1. When I swap my loom/harness over I’ll add to your post if the 98-00 harness is any different.

Edit: Mis read your previous post about the blue wire!
 

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Discussion Starter · #14 ·
What’s very confusing is that Used parts are identified improperly like the FCU I bought—it’s clearly different than my old one. The part number has to be wrong but how can I tell? The module I bought has HC4 stamped on it but I need an HC5. So annoying

The FCU listing you sent me looks like a CDI but the 93 and 94 models list different part numbers; still I have 2 94s and a 95 at work so $17 was an easy call.
 

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I may have a HC5, I know one is HC4 but the other?? Since I plan on using a Ricks hot shot and wire my fan up to a switch I won’t be needing it. I’ll double check tomorrow and let you know. Feeling a little guilty after posting that link and you bought it!
 

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Oh BTW the seller refunded me cuz it was a non-fan alarm unit.
Happy days :) I never had chance today to see if my spare gen2 is a HC5, I’ll look in the morning for you. It will definitely control a fan as it’s from a UK machine.
 
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