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Discussion Starter #1
As far as I can tell my fans have never worked, and since I rarely climb mountains or get stuck in traffic, the problem has only come up 2-3 times while visiting other states. I bought the bike, new '05 bought in '06 and only encountered overheating indications on two trips. I performed some tests outlined in the service manual and eliminated the relay and motors. They work if the relay is grounded at the BRN/RED connector (input from the ECU).
Since the dash Temp gauge works I believe the Temp. sending unit is working correctly. This leaves either the ECM or a connection break between the ECM and the fan relay.?
Since the bike runs perfectly, I don't suspect the ECU and since the dash temp gauge gets it's input from the ECU I'm further convinced it's not the ECU.
I really don't want to take the bike apart any further, so I need some advice from you guys who know a lot more than I do.

Would I be safe in wiring a micro switch to ground the BRN/RED connector of the cooling fan relay so I can turn on the fans manually?

At some point when the bike is being stripped down for something else I'll have the problem corrected.
 

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Vendor
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Yes ... you can put a switch into ground the system like you tested it. But, you should not have to do that. Try this ... make sure your system it correctly filled with coolant first. Start it, and allow it to sit at idle in nuetral and just run. It can take upto 30 mins for them to come on ... maybe longer depending on your climate. Watch the temp guage to make sure it does not go into the red. Your fans will mostlikely come in less then 20 min.

As far as you cooling system over heating. Has the system been flushed every 2yrs or 24k? Make sure there are not leaks by pressure testing the cooling system and cap. How many miles?
 

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GL1800 Doctor
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Philip, the ECT can cause this and the gauge still work fine. In your other post I explained this. http://gl1800riders.com/forums/showthread.php?t=288811 See post#12.

The ECM doesn't drive the gauge. The ECM gets it's info from half of the sensor and the gauge is driven from the other half of the sensor. The ECT is 2 sensors in one. The ECM is also a possibility. There was a board member in the past that had a defective ECM that did this very thing. Just because the bike runs well doesn't mean the whole ECM is fully functional. There is resistance measurements in the service manual for the ECT sensor to test it. It is supposed to be pulled out of the left head to do the test. Goodluck in tracking this down, the possibilities run from a defective ECM, to a bad sensor, to something as simple as a bad connection between the sensor and ECM.
 

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Discussion Starter #4
I have an Engineer friend who is going to help me do some of the tests described in the service manual, I am going to replace the Air cleaner while I have everything exposed. Thanks Techdude2000, we'll try to eliminate things one at a time. I don't want to go into the Temp sending unit, if I can help it.
 

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GL1800 Doctor
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I have an Engineer friend who is going to help me do some of the tests described in the service manual, I am going to replace the Air cleaner while I have everything exposed. Thanks Techdude2000, we'll try to eliminate things one at a time. I don't want to go into the Temp sending unit, if I can help it.
I understand completely, Honda stuck that thing in the hardest place to get to. As an alternative, you can ohm out the harness and the sensor from the ECM's connectors. You won't be able to be precise about the water temp, but it will show you if it's way out of whack and if the connectors and wires are good to it. :thumbup:
 

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Discussion Starter #6
Thanks, after looking for a way to get to it I decided to try the harness. I love the picture in the manual showing the location with the note; (ENGINE REMOVED)! Thanks Honda.....
I appreciate your help techdude2000, There's always that one electronic gadget that can't be accessed or repaired.
 
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