[Alvin]

Hi All. Just bought this 2004 GL1800 with 97,000 kms in 2021. I have never heard the cooling fans kick in not once during the time I've had the bike. However I have never been stuck in a lot of traffic until yesterday. I have driven over 20,000 kms and the fans don't seem useful at all.
What is the most likely area of concern.
1. Do the fan motors seize up and not work?
2. Could the relay under the seat be faulty?
3. The main 20 amp fuse is good.
Appreciate any help I can get, heading out for around the great lakes ride on Thursday the 15th
Alvin

 

[dsurley]

well
first thing.......... how high on the gauge did it go
my fans don't come on until the gauge hits the big hash mark
and you have to be stopped
anything over 10mph and the fans are shut down
It takes a long time before mine heats up enough for them to ever come on unless it is 95+ degree days

 

[GLblinded]

Your’s and mine’s model year (05’) won’t cycle fans in second, third, forth or fifth gears. The fans also blow forward, against air movement when moving slowly, so there is an overheating condition referred to as ‘parade mode’ were 5-10 mph forward movement will cause the engine to heat up, but not allow the fans to push air forward and cool the engine. The directive from Honda was to pull over to the side of the road, keep it running and allow the fans to do there job. Also as was said above, if it isn’t physically discharging coolant out of the pressure relief valve, it is not overheating. The gauges vary in accuracy and may read high, but not be near boilover. Some talk of maintenance, or lack of, that causes a coating buildup in the coolant jackets and acting like an insulator that prevents heat transfer. You should be able to quick test by idling the bike from dead cold to fans cycling while observing the fans performance. it would also be resetting your ECM too! Or you can trace the fan circuits and confirm all is well electrically or find faults and correct. I have heard of fans failing, but haven’t found one bad myself.

 

[Barry Dupler]

If your fans are like mine to even hear them run you have to be in a completely quiet garage, on the road in traffic the only way I know they are working is when I see the gauge move up a little and then back down.

 

[Burnerboy]

I every once in a while (every month/or so) start my bike, and let it run, (without touch'n the throttle) till the fans come on..(usually takes 10(ish) minutes), this "from what I" understands Reset's the ECM .............and bike "seems" to run better...
Is it only my imagination, OR does it work , I REALLY DON'T KNOW But the bike smooths right out.......

Ronnie
9/11/22

 

[dsurley]

I every once in a while (every month/or so) start my bike, and let it run, (without touch'n the throttle) till the fans come on..(usually takes 10(ish) minutes), this "from what I" understands Reset's the ECM .............and bike "seems" to run better...
Is it only my imagination, OR does it work , I REALLY DON'T KNOW But the bike smooths right out.......

Ronnie
9/11/22

you would be correct
I have to do that as the seasons change from summer heat to winter cold

 

[giumbyredd]

Do you know when anti freeze was last changed? If not, it is time.

 

[Midnight Express]

That is sure different than my 2010. When the fans come on it sounds like a Hoover vacuum cleaner. I think there was a bigger radiator in 2006, but what charges were made, if any, to the fans I don’t know.

 

[GLblinded]

That is sure different than my 2010. When the fans come on it sounds like a Hoover vacuum cleaner. I think there was a bigger radiator in 2006, but what charges were made, if any, to the fans I don’t know.

The fans are bigger too!

 

[TerryWerm]

When the fans start up on my '08 you would swear that somebody just started up a big grain dryer! There is no doubt that they are running.

The fans on your '04 may very well be smaller in size and much quieter. If this is the case, when you suspect that they are running (while sitting still) you should be able to feel some warm air movement in the front of the bike, just behind the front fork. If you get your head down there it would be much easier to hear them as well.

If you find that the fans do not start up when the bike is parked and it actually starts to get too warm, there are several things to check:
Blown fuse
Bad temp switch
Bad gear sensor switch
Loose or disconnected wiring connectors

Obviously you would need a good wiring diagram to locate the gear sensing switch, but there must be one somewhere to disable the fans when in the upper gears. It may be possible that the fan shutoff is controlled by speed rather than gear, but this is something that only the manual could help with. I am out of town and cannot look it up in my factory manual for you at this time.

 

[Burnerboy]

When the fans start up on my '08 you would swear that somebody just started up a big grain dryer! There is no doubt that they are running.

The fans on your '04 may very well be smaller in size and much quieter. If this is the case, when you suspect that they are running (while sitting still) you should be able to feel some warm air movement in the front of the bike, just behind the front fork. If you get your head down there it would be much easier to hear them as well.

If you find that the fans do not start up when the bike is parked and it actually starts to get too warm, there are several things to check:
Blown fuse
Bad temp switch
Bad gear sensor switch
Loose or disconnected wiring connectors

Obviously you would need a good wiring diagram to locate the gear sensing switch, but there must be one somewhere to disable the fans when in the upper gears. It may be possible that the fan shutoff is controlled by speed rather than gear, but this is something that only the manual could help with. I am out of town and cannot look it up in my factory manual for you at this time.

Good info too know here!! Thank you !!

Ronie
9/12/22

 

[Techdude2000]

The fans should cycle on and off after the bike gets up to normal temp. This is usually indicated on the gauge by the needle just touching the bottom of the half way mark. If you let it sit and idle, at some point it should cycle both fans on and off.

 

[Alvin]

Oh boy I'm still working on it. Just replaced temperature heat sensor on the motor but did not solve the problem. All new antifreeze now but still no improvement. I've shorted the fans out by bypassing the relay and they both work wonderfully but the heat gauge will go right to the red and never turn cooling fans on. Still stumped.

 

[GLblinded]

Oh boy I'm still working on it. Just replaced temperature heat sensor on the motor but did not solve the problem. All new antifreeze now but still no improvement. I've shorted the fans out by bypassing the relay and they both work wonderfully but the heat gauge will go right to the red and never turn cooling fans on. Still stumped.

Did you try another relay? You also know that half of the relay terminals work, but you need to test the other 2 wires coming into the relay. Got the service manual with wiring diagrams? that will help.

 

[Alvin]

Did you try another relay? You also know that half of the relay terminals work, but you need to test the other 2 wires coming into the relay. Got the service manual with wiring diagrams? that will help.

Is there anyway you can scan the wiring diagram and send it to me. I don't know if that will help or not. I'm seriously just thinking of running a pair of jumper wires to a switch near the handle bars or faring shell and just use a on/off switch because i've only had it overheat when stopped in traffic so its a non issue to just reach down and flip the switch then turn if off when I get moving.

 

[Alvin]

Is there anyway you can scan the wiring diagram and send it to me. I don't know if that will help or not. I'm seriously just thinking of running a pair of jumper wires to a switch near the handle bars or faring shell and just use a on/off switch because i've only had it overheat when stopped in traffic so its a non issue to just reach down and flip the switch then turn if off when I get moving.

Oh yes and I've changed or switched relays and it doesn't change a thing. Thanks for your response.

 

[TerryWerm]

Alvin, no offense intended here, but the temp sensor for the fans is on one of the radiators, but I don't remember which one. Replacing the temp switch on the engine itself will not help you. I don't believe anyone made that clear. There are differences between your '04 and my '08, so my manual may not be correct for your bike anyway. In '06 there were cooling system changes made including slightly larger radiators and larger fans and there may be other differences as well.

 

[bcihil]

Alvin, no offense intended here, but the temp sensor for the fans is on one of the radiators, but I don't remember which one. Replacing the temp switch on the engine itself will not help you. I don't believe anyone made that clear. There are differences between your '04 and my '08, so my manual may not be correct for your bike anyway. In '06 there were cooling system changes made including slightly larger radiators and larger fans and there may be other differences as well.

I just looked all over the service manual, cooling system, water pipe and radiators. No where does is show a fan switch.
The only temperature sensor shown any where is on the cylinder head. That's for water temperature, not the fan.
Even the wiring diagram for the fans does not show the sensor. The only thing it does show is the fan relay is controlled by the ECM. The power is supplied by fuse #7, to the relay coil and then to the ECM

 

[Alvin]

Hey Terry no offense taken. I appreciate any help I can get. I am thankful that you have reached out to assist me in my endeavors to get an almost classic motorcycle back to 100% perfect operating condition. This is the only mechanical thing keeping me held back and worrying about traffic congestion. My normal rides never involve lots of stopped traffic except once in a city and once crossing the Peace Bridge in Fort Erie/Buffalo. Other than that the bike is usually moving. It very well might be the ECM that is the problem and that just seems like an expensive fix. Thanks again Terry for caring for someone in the great white north where one seldom needs to be cooled off.
Alvin

 

[Techdude2000]

Alvin, no offense intended here, but the temp sensor for the fans is on one of the radiators, but I don't remember which one. Replacing the temp switch on the engine itself will not help you. I don't believe anyone made that clear. There are differences between your '04 and my '08, so my manual may not be correct for your bike anyway. In '06 there were cooling system changes made including slightly larger radiators and larger fans and there may be other differences as well.

Nope, the ECT tells the ECM the engine temp and it decides to turn on the relay and fans. There’s probably a bad connection in the circuit between the ECT and the ECM. A little extra resistance in this circuit will cause the ECM to think the engine is cooler than it is and never turn on the fans. The ECT has two different circuits that it feeds, one part of it runs the gauge and the other part informs the ECM of the engine temp. This is the same for all wings 01-17 models. The only change was a different ECT started being used in 06 with the larger radiators. It’s resistance is different to match the newer style ECM.