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Discussion Starter #1
I asked a question last week about when the fans should run and all I can come up with is a bad water temp sensor. I have pressure tested the system replaced the cap with a OEM one replaced the antifreeze again just to make sure there was no air pockets and my fans still won't come on till my temp gets 2 bars past half way and until this year it always stayed at half way.

Has anyone replaced there water temp sensor for this problem and has it made a difference? It looks like a lot of plastic has to come off to get to it so I would like to be sure before I give it a try.
 

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Are we talking about a static test or riding conditions? Above 22 mph or so the fans will not.kick on.

2007... still under warranty?
 

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Discussion Starter #3
Are we talking about a static test or riding conditions? Above 22 mph or so the fans will not.kick on.

2007... still under warranty?
Under 22 when sitting still or very slow traffic. Never goes past half way at driving speed.

Still under warranty 91,000 miles and never been in the shop like to keep it that way.
 

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I had the exact same issue last year on my 06... The fans came on at about the 3/4 mark on the gauge (way to late)... I changed out the temp sensor with no change in the condition... There really is only two things that control the fans... The temp sensor and the ECU...

I was able the cure the problem by unplugging then cleaning and lubing every possible connector I could get to... Once I did this and yet another reset of the ECU everything has been good since... Also insure you burp the air out of the cooling system...
 

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Do you have a non contact pyromiter?

if so, start the bike and aim it at the radiators to check the temp.


It takes quite a while in moderate tempatures for the fans to kick on.

BTW, what is the shop manual procedure to check this?
 

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Discussion Starter #6
I had the exact same issue last year on my 06... The fans came on at about the 3/4 mark on the gauge (way to late)... I changed out the temp sensor with no change in the condition... There really is only two things that control the fans... The temp sensor and the ECU...

I was able the cure the problem by unplugging then cleaning and lubing every possible connector I could get to... Once I did this and yet another reset of the ECU everything has been good since... Also insure you burp the air out of the cooling system...
That would be a good try I guess it would be the connector from the sensor to the harness or the ECM connector. Thanks
 

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I just opened my 2006-2010 GL1800/A service manual and the procdeure for checking the ECT sensor starts on page 21-35.
 

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I have the same problem with my 2006. When new it would never go over half way before the fans came on. Now it goes to the first line over half and then the fans kick in. I replaced my temp sensor a couple of years ago and it made no difference. I'm convinced there is air in the system somewhere because it was going higher than that before I used the UView AirLift system. I just haven't been able to get it to work like when it was new but I don't worry about it anymore.
 

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To varify air is not in the system. Do just as the Service Manual says. Remove rad cap, fill, install cap. Run 2-3 min. snapping the throttle a couple of times. Uncap and add as needed. I do this while running. No special equipment is needed and this method works for an engine that is warm of cold. Then, while running I begin to check of fill the recovery bottle. Once it comes up to operating temp. I turn it off. The coolant in the engine will then begin to expand and fill (burp or prime) the recovery hose. For the next couple of minutes you can see this by rechecking the dip stick ... the coolant level gets higher. Restart it, run to operating temp., top off resevior to top notch. Ride it for a couple miles and recheck and add as needed.

You may have a stuck thermostat.
 

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I would put a new thermostat/water pump on the bike. But that is me.

Would be my first step.
 

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I would put a new thermostat/water pump on the bike. But that is me.

Would be my first step.
I might too ... it would at least be nice to know year and milage.
 

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Discussion Starter #13
I would put a new thermostat/water pump on the bike. But that is me.

Would be my first step.
I can't see that being a problem it never runs hot when riding it only get hot sitting at a long light or very slow traffic. If I had a bad pump or thermostat the fan still should be running before I get to 3/4 on the gauge.
 

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Rich, if you can find an electronics parts place or even a TV repair shop, buy a .7 ohm resistor and put it across the 2 pins at the ECM connector that go to the temp sensor. This will make the ECM "think" the engine is at 245-275 degrees and the fans should come on. If they don't then you have a faulty ECM. If they do come on, then your temp sensor or the connections to it need attention. The connections are the most likely culprit for this. The ECM "sees" the resistance of the sensor as it heats up. The resistance of this sensor drops to almost a short when the engine is at normal temp. Just a small amount of resistance in this circuit will trick the ECM into "thinking" the engine is colder than it is.
 

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I can't see that being a problem it never runs hot when riding it only get hot sitting at a long light or very slow traffic. If I had a bad pump or thermostat the fan still should be running before I get to 3/4 on the gauge.
Yes ......do the test Techdude told you about. Many times I assume the basics have been done. It very well could be the sensor and or the ECU itself. A bit of extra resistance could cause the temp gauge itself to be incorrect.

Burping air.....I get so tickled at that one. Burp the air, gotta be the air. Lol! I wonder if they use a towel and put the bike over their shoulder. I mean air rises to the top ,there is a pump impeller that circulates the coolant and as soon as the bike comes to temp and the thermostat opens if there is any air in the system it is gone almost instantly .

But a bad thermostat can cause the bike to heat up. No flow it restricts the flow as can a worn impeller . As the thermostat is a part of the pump hence just replace the whole thing then you have a new impeller also.

In your case it is the sensor, the gauge and or the ECU. Either the sensor is not turning on the fans, or the gauge itself is reading hotter than the bike is actually running.

You will need a manual and test each component to find the exact cause.
 

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Discussion Starter #17
Rich, if you can find an electronics parts place or even a TV repair shop, buy a .7 ohm resistor and put it across the 2 pins at the ECM connector that go to the temp sensor. This will make the ECM "think" the engine is at 245-275 degrees and the fans should come on. If they don't then you have a faulty ECM. If they do come on, then your temp sensor or the connections to it need attention. The connections are the most likely culprit for this. The ECM "sees" the resistance of the sensor as it heats up. The resistance of this sensor drops to almost a short when the engine is at normal temp. Just a small amount of resistance in this circuit will trick the ECM into "thinking" the engine is colder than it is.
Thanks leaving on a 5000 mile trip so I don't want to touch it now I will look into it this winter when I do maintenance. Like I said not a big problem just don't like it getting hot before the fans come on.
 

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Thanks leaving on a 5000 mile trip so I don't want to touch it now I will look into it this winter when I do maintenance. Like I said not a big problem just don't like it getting hot before the fans come on.
Oh ... you scared me with the 5000 trip. Thought you might be taking the Wing. I was going to say that cooling system is #1 breakdown on todays highways ... of coarse that is referring to cages. But, our Wings have to be maintained as it they are a cage.
 

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Discussion Starter #19
Oh ... you scared me with the 5000 trip. Thought you might be taking the Wing. I was going to say that cooling system is #1 breakdown on todays highways ... of coarse that is referring to cages. But, our Wings have to be maintained as it they are a cage.
I am taking the wing and the fans do come on but only after half way closer to 3/4 and then temp drops back to half way. The bike never goes over half way while ridding. It has been like this all year and I have 20,000 this year I just want to get it back to were the fans run before the temp goes over half way. Looks like ED Z had the same problem and he fixed his by cleaning connectors from the water sensor to the ECM so that will be my first try.
 

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Rich,
What techdude says makes sence (small amount of resistence can confuse the ECM)... The cure for mine was to clean and lube the ECM plugs (as well as others while I was at it)... There are only two items that control the fans... The temp sensor and the ECM (and of course the wire between em)... Get some plastic safe contact cleaner and a good terminal lube and have at those connectors...
 
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