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Discussion Starter #1
I have a question for you guys. My '06 LT is/was overheating in traffic. No red light but does peg the graphic display. Anyway the dealer says the computer doesn't show anything wrong. When he demonstrated, in fact the fans did come on, but while we were talking they went back off and never came back on again. He suggested maybe trying the sending unit but he didn't have one in stock. It was last fall so I road anyway and with the cooler weather everything went ok. They ordered the sending unit and I took my bike back for it's 12k service this spring. I got a different mechanic and the computer still showed nothing but the bike did get a little warm in trafic on my way to the dealership (50 miles) so I assume the fans didn't come on. Actually I know they didn't because you can put your hand down and feel them when at a stop, and they weren't coming on. I personally thought since the sending unit is nothing more than a glorified thermo-couple, it would probably either work or not work, not intermittent. Anyway after begging to spend $15 while the bike was opened up anyway I convinced them to replace the fan relay. It seemed to me to be the only thing that could malfunction in a come and go fashion. I haven't had it in any traffic since.

Any other thoughts?
 

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2005 K1200LT
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The sending unit is the one at the rear of the cylinder head. It feeds the Motronic unit which in turn activates the fan relay. It also tells the Motronic the current engine temp. So if that was bad you would have drivability issues. Have seen a few relays go bad so that was a wise choice. There have been ground issues with the fans as well. It should never peg the bar graph.
 

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Discussion Starter #3
jzeiler said:
The sending unit is the one at the rear of the cylinder head. It feeds the Motronic unit which in turn activates the fan relay. It also tells the Motronic the current engine temp. So if that was bad you would have drivability issues. Have seen a few relays go bad so that was a wise choice. There have been ground issues with the fans as well. It should never peg the bar graph.
OK Since my first post I have had my bike, warmed it up then put it on the center stand and let it idle, and the fans still do not come on. Bar graph gauge goes straight to the top. Any other suggestions? If I'm reading your reply correctly, if the sending unit is bad the bike will have running issues as well? It seems to run fine, unless I'm missing something. Does the sensor control the relay directly or does the computer control the relay? I take it back to the shop Thursday morning but over the phone it sounds as though they still don't know what to do. This will be the third time it's been opened up, and I would really like to get it right this time. They want me to leave it so they can "test ride" it. I keep telling them when it's moving it's fine, it's only when stopped that it heats up. I can see one of them riding it out into traffic, getting hot, and trying to get back to the shop rather than shutting it down. Paranoid, I know :eek:
 

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I had something similar happen with my 05 LT. The bar graph would peg out but my fans did come on when needed. Computer show the fans coming on when they should, but the gauge would remain pegged. If I stopped and turned the bike off and then on the gauge would work normally for a short time and then peg.

The shop replaced the instrument panel and that didn't fix it. The next thing they did was to go over every connection, clean and resolder when needed and solder a few that hadn't been. It fixed the problem. It's been about 6 months now and the temp gauge is working fine.
 

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The sensor feeds the motronic and the motronic decides when to turn on the fans. rab 1967's problem does not bode well as those type of faults are very hard tofind and get $$$$ at the dealership. Sounds like they replaced the relay so the next thing I would check is the actual temperature. Harbor Freight has some inexpensive non-contact thermometers. Next time you have a pegged gage shoot the radiators and head to see what the temps are. Could be your gage is off due to a faulty feed to the dash. The temp sender for the gage is up near the water pump right next to the oil pressure switch.


Temps are as follows: T stat opens @ 185 F, Fan cut in temp @ 221 F, High Temp Light @ 239 F
 

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Discussion Starter #6
jzeiler said:
The sensor feeds the motronic and the motronic decides when to turn on the fans. rab 1967's problem does not bode well as those type of faults are very hard tofind and get $$$$ at the dealership. Sounds like they replaced the relay so the next thing I would check is the actual temperature. Harbor Freight has some inexpensive non-contact thermometers. Next time you have a pegged gage shoot the radiators and head to see what the temps are. Could be your gage is off due to a faulty feed to the dash. The temp sender for the gage is up near the water pump right next to the oil pressure switch.


Temps are as follows: T stat opens @ 185 F, Fan cut in temp @ 221 F, High Temp Light @ 239 F
Would this be true if the guage reads normal out on the road?
 

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rswisher said:
Would this be true if the guage reads normal out on the road?
I keep thinking that 'one' of your fans is NOT working. You have two radiators and two fans and while on the road, you 'should' see normal readings on the display and the fans will usually NOT activate if you're moving at normal speeds. However, slow traffic and/or idling, if one fan isn't working, the other fan cannot make up for the lack of airflow. I know you said you can feel the air movement by the fans - you mean 'both' of 'em?

I don't know the fuse arrangement on the newer model year LTs, but ole Toad has a fuse for each fan, located under the passenger seat. Yours are good??

Good luck in getting this resolved. You're getting some good help from folks who aren't there to experience what you are. Take care.
 

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My LT is older but I think the digital displays are similar in their calibration relating to temperature. On my LT the fans do not come on until the gauge is almost topped out. They come on just short of the red mark on the gauge. This is normal, so you should see the bar get close to the top of the scale before the fans kick on. Is it possible you are expecting them to kick on too soon? Look at the figures John gave. Thermostat is set at 185 which on my bike is just below 1/2 on the gauge. 221 the fans come on and that's just below the red mark on the gauge. So if the gauge isn't almost pegged, the fans won't normally be on. It's different than on a car or truck where the temperature is designed to remain constant. The LT will show a large swing on the gauge in stop and go traffic and that is normal.
 

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The fan cut in near the red is normal for the non-digital dash bike but the fans should cut in about 1/4 inch above center on the newer bikes. I have never seen mine go more than 3/8 inch above center.
 

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Discussion Starter #10
Thanks. I was just going to type the same thing. Dick, I know BOTH fans are not comming on. Fuses are good. Here's a new wrinkle. I took the bike to the shop Thursday morning and when I got there I let it idle to see what would happen. As usual, the fans didn't come on and the graphic display topped out. I switched the bike off and in about 30 seconds I switched it back on (I didn't start it at this point) Both fans came on and the temp warning light was on. I started the bike and it quickly cooled down and the fans eventually shut off, and never came back on, so I switched the bike off again. That's right, you guessed it, when I switched it back on. everything came on. Fans, light, the whole works. I hate to say it but it sounds like a computer problem to me. I'm calling to check on it in a couple minutes.
 

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Discussion Starter #11
Re: 06 Lt Fans Not Com.ming On In Trafic

Well, it's fixed. It turned out to be the temp sensor the mecanic originally thought. The computer showed no errors, but replacing the sensor fixed the problem.

Thanks to all for your help. They really seemed to listen to what you all had to say.

Thanks again

:D :D :D :D :D
 

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I always love a happy ending!:wave
 
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