Radiator fan not working...how to fix

[quad2xtreme]

Hoping someone...like DBRACING can give me some guidance.

1) The fan works when I ground the green wire off the blue connector under the hood. I used a sharp probe to pierce the wire casing for this step. I will put a dab of silicone on it when I am done.

2) The fan does not work when I directly ground the temperature sensor wire although the red light on the dash does turn on.

3) I tested using a different keyswitch from another 2006 450er I have.

4) I know just enough about electricity to make a fool of myself. Hence, thinking that #3 might have anything to do with this. :)

I could direct wire the green wire to keep the fan on all the time but I've read this isn't a good place to do it since it is getting a direct ground and the fan isn't designed to pull full power from both the positive and negative side. From what I understand, the temperature sensor wire runs through some other little magic box first that reduces the power in some form or fashion.

I was planning to put a toggle switch on the temperature sensor wire so I could have the best of both worlds...a functioning temperature sensor as well as a direct switch so I could put the fan on if I wanted.

Planning a trip in a week and have 2 days this weekend to get everything ready. Any help is appreciated.

[hondarider421]

i know its not the best idea but y not stick the fan on a toggle switch itself and then when the light comes on turn the switch on or just once she gets to opperating temp turn it on i mean i know its not the best but it will work for ur trip and thats wat we do to drag bikes but thats alot diff they get really hot really quick

[quad2xtreme]

Problem solved...I guess.

I was getting ready to replace the "black box" with the one on my other 2006 as a test but decided maybe it wasn't drawing enough power because the quad wasn't running. When I started it, the fan started working. So, I assume all is well now. I tested this way at the very beginning so I am guessing the electrical connector wasn't making good enough contact.

[DnB_racing]

Originally posted by quad2xtreme
Problem solved...I guess.

I was getting ready to replace the "black box" with the one on my other 2006 as a test but decided maybe it wasn't drawing enough power because the quad wasn't running. When I started it, the fan started working. So, I assume all is well now. I tested this way at the very beginning so I am guessing the electrical connector wasn't making good enough contact. do you have a R or ER? your sig says R,

I hope its an ER, if not its funny as hell if you were trying to run a fan without any power.lol:blah: sorry I couldn't resist

but as far as your original question about the frame ground, and not using the cdi ground,

Yes your right! its best to use the cdi ground, it has to do with the fact that the fan uses the regulated circuit,

if you run the fan from a frame ground it will discharge the battery quicker,

when using the regulated circuit, the regulator supplies enough to use all the auxiliary circuits, and charge the battery 13.8 volts,and any volts that the reg makes over whats needed to give a full charge is discharged through resistors and dissipated through the heat fins of the regulator,

so basically as long as the quads running you dont actually discharge the battery, only charge

but if you wire it not on the regulated circuit,the whole time the fan is actually drawing from the battery instead of the regulator, making it hard for the battery to remain full charged while running, and putting the load of the fan on the battery instead of the regulator

[quad2xtreme]

ah yes, the signature. I recently bought a 2006 450er as a trail quad so I stopped the temptation of running my mx quad in the wood.

[jaspurx]

I was on here looking for some info. to help with my fan that doesn`t run at all (yet)
I just bought a used, totally stock `07 trx450er.
on the second ride we rode the tighter trails, which kept me third gear and lower. I noticed excessive engine heat on my legs, and some steam coming up from under the plastic when I stopped. The red light isn`t staying on after starting back up, but the fan isn`t running at all.
For now I`m just letting her cool back down when it gets hot enough to push antifreeze out and start steaming.
It seems like it is overheating, but the red light isn`t staying on for more than a few seconds after starting up.
Yes, I keep the coolant topped off.
yes, I checked the wires , all are plugged in.
I`m not certain to start with a new thermostat, or check the fan wiring, etc.
The honda shop manual gives no direction on checking the fan.
After reading this post, if I read correctly,I should be alright to direct to battery hot wire to check if the fan runs at all and go from there, correct?
I didn`t want to direct wire the fan to check it if it was on a reduced(from 12v) power suply and fry the fan, but it`s my first logical step to diagnose my problem before starting parts replcement elimination (dealership mechanic methods) which can add up $$$ rapidly

[quad2xtreme]

Start you quad so it is idling. Then,
take the temperature sensor wire off the temperature sensor at the front of the motor and ground that to the engine with an extra piece of wire. At that point, the red light on the dash should come on and the fan should spin. 100% sure you won't cause any damage from testing this way.

If this doesn't work, I'd disconnect and re-connect the blue connector under the hood on the left side...should be facing you.

If that doesn't solve it, I'd check the fan next. Trace the fan wire back to the blue connector under the hood. disconnect it. Take one of the wires direct to the positive post on your battery and the other to the negative. The fan should spin. If not, you have a fan problem. You have to get it spinning before you worry about anything else.

I use leads that have a pointy probe on one end and alligator clips on the other.

/Jon




Originally posted by jaspurx
I was on here looking for some info. to help with my fan that doesn`t run at all (yet)
I just bought a used, totally stock `07 trx450er.
on the second ride we rode the tighter trails, which kept me third gear and lower. I noticed excessive engine heat on my legs, and some steam coming up from under the plastic when I stopped. The red light isn`t staying on after starting back up, but the fan isn`t running at all.
For now I`m just letting her cool back down when it gets hot enough to push antifreeze out and start steaming.
It seems like it is overheating, but the red light isn`t staying on for more than a few seconds after starting up.
Yes, I keep the coolant topped off.
yes, I checked the wires , all are plugged in.
I`m not certain to start with a new thermostat, or check the fan wiring, etc.
The honda shop manual gives no direction on checking the fan.
After reading this post, if I read correctly,I should be alright to direct to battery hot wire to check if the fan runs at all and go from there, correct?
I didn`t want to direct wire the fan to check it if it was on a reduced(from 12v) power suply and fry the fan, but it`s my first logical step to diagnose my problem before starting parts replcement elimination (dealership mechanic methods) which can add up $$$ rapidly

[DnB_racing]

^^x2^^

if you have a multi meter you can also check the black wire at the same blue connector,

with the quad running the black should allways have power, the green wire from the cdi to the fan will only complete the curcuit when the temp sensor calls for it

[DnB_racing]

Originally posted by jaspurx
I was on here looking for some info. to help with my fan that doesn`t run at all (yet)
I just bought a used, totally stock `07 trx450er.
on the second ride we rode the tighter trails, which kept me third gear and lower. I noticed excessive engine heat on my legs, and some steam coming up from under the plastic when I stopped. The red light isn`t staying on after starting back up, but the fan isn`t running at all.
For now I`m just letting her cool back down when it gets hot enough to push antifreeze out and start steaming.
It seems like it is overheating, but the red light isn`t staying on for more than a few seconds after starting up.
Yes, I keep the coolant topped off.
yes, I checked the wires , all are plugged in.
I`m not certain to start with a new thermostat, or check the fan wiring, etc.
The honda shop manual gives no direction on checking the fan.
After reading this post, if I read correctly,I should be alright to direct to battery hot wire to check if the fan runs at all and go from there, correct?
I didn`t want to direct wire the fan to check it if it was on a reduced(from 12v) power suply and fry the fan, but it`s my first logical step to diagnose my problem before starting parts replcement elimination (dealership mechanic methods) which can add up $$$ rapidly I dont mean to scare you, but if the fan does work when you ground out the temp sending unit, it could be a worse problem...

it might not actually be overheating but over pressurising from a bad head gasket or worse...

hope for a fan issue:scary:

[jaspurx]

Thanks guys, I just wanted to start with a little confirmation on he fan being 12v for sure and go from there to trace the problm back to the source.
It was bothering me to throw 12v to a fan motor that was reduced down from 12v to 9.6v or much less and frythe fan motor trying to test it.

I dislike the normal parts changing process of elimination of some "mechanics" instead of diagnosing the problem first.

I hope its just a fan , sending unit or thermostat problem and not worse.

All this for my practice/trail quad , yet another reason to make the `05 my racer ( simplicity)lol

[jaspurx]

OK guys, the cooling fan does work, and the light does come on when I groung the temp. sensor wire to the engine while the engine is running.

Diagnosis?

Should I start with the temp. sensor or the thermostat ?

I am tempted to put a simple grounding wire ran through a toggle switch on the temp sensor wire ( eliminating the temp. sensor) and kick it on when the engine gets up to operating temp. while riding until I get this resolved.

Thanks guys

[quad2xtreme]

definitely the temp sensor.

[DnB_racing]

Originally posted by jaspurx
OK guys, the cooling fan does work, and the light does come on when I groung the temp. sensor wire to the engine while the engine is running.

Diagnosis?

Should I start with the temp. sensor or the thermostat ?

I am tempted to put a simple grounding wire ran through a toggle switch on the temp sensor wire ( eliminating the temp. sensor) and kick it on when the engine gets up to operating temp. while riding until I get this resolved.

Thanks guys you can check the thermostat, it should start opening at around 175-180 degrees,and make sure there is no teflon tape on the threads of the sending unit,

one thing also is make sure your getting flow, before starting,take radiator cap off and start it and let it come up to temp there should be movement if not it could be a water pump.

if it wants to boil over then there is a chance its pressure from a bad head gasket or cracked head...

but in the mean time you can try running it with a toggle like you mentioned, but keep a close eye on everything there might be other issues besides just the fan not working

i can ride my quad for hours and the fan doesnt come on,be careful not to overheat and cause damage

[jaspurx]

Thanks guys,
Thats exactly my point, looking out for a potential bigger problem while I go through this process.
My 05 doesnt get nearly this hot is why I am being cautious of how hot to let it get.
I figure if "switching" the sensor wire doesn`t help enough then it is either the thermostat or a bigger problem.

I prefer a liquid cooled trail/practice quad to say my trx400ex for example, and with the hillclimbs I practice on, the trx400ex is too heavy and underpowered.
I also prefer to practice on a quad that is closer to my race quad.

The 250R is just too much for the tight trails we ride on, it gets too hot as well, and overheats coolant out, just like the 450er does now.