2002 Honda Foreman 450 ES Getting Extremely Hot

[DeTaylor 48]

8 minutes ago, jeepwm69 said:

 

That's usually backfeeding/wire grounding out somewhere (the dim light)

 

Have the same issue on my buddy's 450 I'm working on now.  I haven't had time to dig further into it after hooking up a battery and finding both Neutral and Reverse lights are both on at the same time (but they're dim as you mention)

Oddly enough the reverse and neutral lights are working just fine. Even the temp light works great on start up. Only when driving does it seem dim. 
 

I’ll ground it out and see what happens. I really don’t think the fan will turn on lol I’ve checked quite a few times and never seen it move. 

[DeTaylor 48]

On 5/18/2022 at 10:34 AM, AKATV said:

Was key on when you jumped wire?

it has to be on for the fan to come on

If so, you can put FCU in oven @ 450 for

7-8 minutes- it will bring them back a lot of times  as failed internal solder joints causes most issues

Also, make sure fan is good by powering up directly

 

Might be a dumb question but do I have to prep the FCU in anyway before exposing it to 450 degrees of fury? 

[AKATV 820]

Nope -just unplug it, put it on a piece of tinfoil or a pie tin with the plug side facing up preheat the oven put it in there for 7-8 minutes and let it cool down without touching it and give it a try

sometimes it takes a second cooking but it’s definitely worth a shot if it’s not working to begin with as you have to get a new one anyways right?

I’ve had very good luck with this -let us know how you make out

it helps to troubleshoot everything else first just to make sure

make sure your fan is functional by applying 12 V directly to it

You can test the temperature sensor on the bottom of the engine by heating it up and checking the resistance as per the manual as well

what I have found through the years for the most part is if you turn your key on and the red light for the temperature does not come on for a second or two and then go out, it’s generally the fan control unit

also if you ground the blue single wire behind the right rear fender either to the frame or to the negative side of the battery and the fan does not come on it’s also generally the fan control

At that point, I’ll just bake the fan control unit and if it doesn’t fix it after the second bake, I will replace it but I generally find it works better than 80% of the time with some of them still continuing to work many many years down the road

 

[DeTaylor 48]

1 minute ago, AKATV said:

Nope -just unplug it, put it on a piece of tinfoil or a pie tin with the plug side facing up preheat the oven put it in there for 7-8 minutes and let it cool down without touching it and give it a try

sometimes it takes a second cooking but it’s definitely worth a shot if it’s not working to begin with as you have to get a new one anyways right?

I’ve had very good luck with this -let us know how you make out

it helps to troubleshoot everything else first just to make sure

make sure your fan is functional by applying 12 V directly to it

You can test the temperature sensor on the bottom of the engine by heating it up and checking the resistance as per the manual as well

what I have found through the years for the most part is if you turn your key on and the red light for the temperature does not come on for a second or two and then go out, it’s generally the fan control unit

also if you ground the blue single wire behind the right rear fender either to the frame or to the negative side of the battery and the fan does not come on it’s also generally the fan control

At that point, I’ll just bake the fan control unit and if it doesn’t fix it after the second bake, I will replace it but I generally find it works better than 80% of the time with some of them still continuing to work many many years down the road

 

Looks like I know what I’m doing tonight. Thank you so much!

[AKATV 820]

If you grounded that blue wire behind the right rear fender and the fan did not come on with the key on then you might want to make sure that your fan works by applying 12 V directly to the fan to make sure that it’s operational first

No sense baking that fan controller 

until you know that your fan is working

[DeTaylor 48]

3 hours ago, jeepwm69 said:

 

Single wire going to the back of the engine, goes onto the temp sensor. 

 

Pull that wire off, and ground it on the engine with the key on.  Fan should come on at that point, along with the temp light

ignore this - figured it out 
 

Another dumb question. Do you pull the wire off the sensor side or the fender side? Looks like someone has done some custom wiring on the fender side. 

Edited June 20, 2022 by DeTaylor

[DeTaylor 48]

1 hour ago, AKATV said:

 

also if you ground the blue single wire behind the right rear fender either to the frame or to the negative side of the battery and the fan does not come on it’s also generally the fan control

 

So I grounded it and the fan did in fact come on. What does this mean then? Appreciate all the help!

[jeepwm69 7,599]

11 minutes ago, DeTaylor said:

So I grounded it and the fan did in fact come on. What does this mean then? Appreciate all the help!

Points to your fan sensor being bad.

when the old temperature reaches a certain point, the sensor grounds that wire cutting the fan on.

 

That said, if you have top end issues that are causing it to get hot really quickly, the oil temp sensor will not cut the fan on because all of the heat is on the top end.

 

I had a 500 with a bad oil pump, and the top end got scorching hot really fast because there was no oil going to the top end. The fan never came on because the oil in the bottom of the crank case was not hot.

 

Does that make sense?

 

[DeTaylor 48]

1 minute ago, jeepwm69 said:

Points to your fan sensor being bad.

when the old temperature reaches a certain point, the sensor grounds that wire cutting the fan on.

 

That said, if you have top end issues that are causing it to get hot really quickly, the oil temp sensor will not cut the fan on because all of the heat is on the top end.

 

I had a 500 with a bad oil pump, and the top end got scorching hot really fast because there was no oil going to the top end. The fan never came on because the oil in the bottom of the crank case was not hot.

 

Does that make sense?

 

Makes sense, atv doesn’t seem to be getting excessively hot in any way. Think the fan sensor may be the culprit. Might also explain the light being dim and coming and going. 

[DeTaylor 48]

1 hour ago, jeepwm69 said:

Points to your fan sensor being bad.

when the old temperature reaches a certain point, the sensor grounds that wire cutting the fan on.

 

That said, if you have top end issues that are causing it to get hot really quickly, the oil temp sensor will not cut the fan on because all of the heat is on the top end.

 

I had a 500 with a bad oil pump, and the top end got scorching hot really fast because there was no oil going to the top end. The fan never came on because the oil in the bottom of the crank case was not hot.

 

Does that make sense?

 

Pretty sure the issue was a loose sensor. It occurred to me that this started after running through swampy woods last week. Plug was loose and dirty. Cleaned it up, took it for a hard 4 miles around the block and back through the woods for 15 min - no light at all. 
 

i am curious though if I should still check the oil pump. Got me worried now 

[Goober 1,555]

Put some permatex dielectric grease on the connector contacts and boot to keep contamination out

[Fishfiles 20,145]

11 hours ago, DeTaylor said:

 It occurred to me that this started after running through swampy woods last week.

 

 

Do you know about keeping the oil cooler fins cleaned out , they will get clogged up with mud pretty quick , depending on your riding conditions , sqampy woods , sounds like something I would do 

[DeTaylor 48]

1 minute ago, Fishfiles said:

 

 

Do you know about keeping the oil cooler fins cleaned out , they will get clogged up with mud pretty quick , depending on your riding conditions , sqampy woods , sounds like something I would do 

Yessir. After reading through this thread that was the first thing I cleaned up. They weren’t completely clogged but there was a bit of dirt in there. 

[jeepwm69 7,599]

14 hours ago, DeTaylor said:

Pretty sure the issue was a loose sensor. It occurred to me that this started after running through swampy woods last week. Plug was loose and dirty. Cleaned it up, took it for a hard 4 miles around the block and back through the woods for 15 min - no light at all. 
 

i am curious though if I should still check the oil pump. Got me worried now 

I wouldn’t worry about your oil pump.  
 

Mine was a fresh rebuild and had had a catastrophic failure before I picked it up.  Piston bits everywhere in the bottom end and I think that’s what gaumed up the oil pump. 
 

The “break in” ride I could tell something wasn’t right so I ruined a nice fresh bored cylinder and pulled the engine and found the problem.  

[DeTaylor 48]

Well my mysterious red light of doom continues. I was paranoid that I still had an issue when my light flashed at me the other day. Ordered a oil temp sensor from PSN and now the light is on pretty consistently. The odd part - my fan still isn’t kicking on. As stated above, my fan does turn on if I ground out the oil temp sensor wire.

 

i don’t have any clue where to turn next. 
 

not sure if it matters - the light was not on right away. I had to hit a few bumps first (wiring somewhere???) and then the light kicked on. 

[AKATV 820]

Have you tried baking your fan control unit at 450 for 7-8 minutes and see if the problem goes away?

Pretty common to have oil temperature control lights on and off with a faulty fan control unit

[DeTaylor 48]

1 minute ago, AKATV said:

Have you tried baking your fan control unit at 450 for 7-8 minutes and see if the problem goes away?

Pretty common to have oil temperature control lights on and off with a faulty fan control unit

I was avoiding this, but I think this is the next test! 

[DeTaylor 48]

@AKATV here we go! Just to verify, the green plastic clips stay on? 

[AKATV 820]

Spoiler

 

You don’t need to wrap it up in tinfoil  just place it with the green plug side up on a pie pan or piece of aluminum foil and don’t move it until it cools down

When you’re talking about green clips are you talking about the female plug that’s attached to the module itself?

[DeTaylor 48]

2 minutes ago, AKATV said:

  Reveal hidden contents

 

You don’t need to wrap it up in tinfoil  just place it with the green plug side up on a pie pan or piece of aluminum foil and don’t move it until it cools down

When you’re talking about green clips are you talking about the female plug that’s attached to the module itself?

Female plug ends - Yes that is correct. I’ll remove the wrapping. 

[AKATV 820]

It’s part of the module and it’s not removable -they are heat tolerant to 450

and will not melt if that’s what you’re worrying about

 

[DeTaylor 48]

That’s exactly what I was worried about. Thank you for relieving that stress! Going in the oven now 

[AKATV 820]

Once you cook it and let it cool down , get it hooked up and when you turn the key on the light should come on for a couple seconds and then go out- that’s a good indication

 then, if you ground that blue wire under the right rear fender on the harness side and your fan and the light both come on and then goes off when you disconnect it -that’s another good sign

Then its just a matter of heat cycling the engine to test to make sure the fan comes on and off as it should

if it doesn’t work the first time, you can try cooking it a second time -if it fails again its time for a new fan control module

you can pick one up on eBay used generally for around $25 or so 

[Fishfiles 20,145]

I have a 450ES part bike , years ago while stripping parts off of it , I noticed the wiring harness was damaged from hitting the frame , it was from the factory like that , I have a pic of the spot somewhere on my desktop  ----  it is on the right side , on the front side of the air box , where the wiring harness goes from top side the frame to the bottom side of the frame , it had rubbed on the edge of the frame and damaged the wiring , the harness had to be pulled away from the frame to see the cut 

 

Check the spot I mentioned 

[DeTaylor 48]

@Fishfiles I’ll give it a look. I would guess that this would be negated since everything works when I ground out the wire from the backside of that harness.