K1200LT Left radiator blower - BMW Luxury Touring Community
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post #1 of 7 Old Nov 27th, 2011, 1:38 pm Thread Starter
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K1200LT Left radiator blower

I have been trying to run down an electrical problem on my bike that led me across another problem.
I found that the 4 amp fuse for the left radiator blower was blown. I rep[laced it and took the bike on a 75 mile ride to see if my battery would charge and also to check the blower.
Got back to the house. It was 66 outside but the bike radiator temp was at 60%. Checked right blower - going full blast! Nothing form the left blower. Killed the bike and it would not restart - dead battery. But I did check the left blower fuse and it was fine.
If I pull the left side of the bike will I be able to trace down the lead to the blower and see if it is something simple like disconnected. In like manner if I can locate the lead can I jump the wire direct to the battery and just see if the blower is burnt out?
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post #2 of 7 Old Nov 27th, 2011, 2:03 pm
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Re: K1200LT Left radiator blower

you will need to ground the (brown) ground wire and put battery on remaining wire, but first see if the motor turns freely by hand to see if it is (partially) seized

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post #3 of 7 Old Nov 27th, 2011, 3:49 pm
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Re: K1200LT Left radiator blower

The cowling for the radiator fans has been one of my LT nemeses.

The last time I struggle for hours to get the cowling back on and aligned I stumbled upon an easy way to get it all lined up again--the radiator is mounted in rubber. So, one can gentle pull the radiator towards the front of the bike and easily remove/reinstall the dam cowling!

The fan has a white molex type polarized connector near the fan.

The fan, I assume, runs on 12 volts. So any 12 volt DC source (battery charger, wall wart etc) should be able to power it.


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post #4 of 7 Old Nov 27th, 2011, 5:01 pm
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Re: K1200LT Left radiator blower

You may have a bad motor on that side. The fan relay feeds both of the fuses (l & r) and the fuses, in turn, service only thier respective fans and nothing else. If it was blown then I suspect a bad motor.

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post #5 of 7 Old Nov 27th, 2011, 6:26 pm
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Re: K1200LT Left radiator blower

I had that exact same problem....left fan stopped running and a blown fuse; right fan ran constantly. Mike at LoneStar BMW checked the mapping on the motronic and it all seemed fine and got the fan to stop running constantly. Replaced the left fan and matching fuse and fan doesn't work....I confirmed it does before installing. I traced the wires and didn't find anything wrong. Hooked it to a GS911 and it says no connectivity (fault). I'm just as stuck as you are....hopefully someone will have the fix to our problemo!

I've run in 106 degree heat here in Texas with one fan and it gets up to about 70-75%, but that's on the open highway....wouldn't want to try it in those temps while sitting in traffic.

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post #6 of 7 Old Nov 27th, 2011, 7:03 pm
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Re: K1200LT Left radiator blower

I looked at the print and like John noted both the fan fuses share the same power feed from the fan relay.
Did you check voltage at the fuse or just check that the fuse is good? It's possible the jumper connecting the two fan fuses failed so you only get one side.
The fans also share a ground but check where they tie together or add a temp ground to the left fan from the battery ground.
You can also feed power to the left fan power feed at the fuse boxf direct from battery, use a protected jumper wire.
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post #7 of 7 Old Nov 27th, 2011, 7:35 pm
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Re: K1200LT Left radiator blower

Turn the key to off and then pull the fuse that was blown and then measure the resistance to the negative side of the battery (or ground) with an Ohm meter. It should be the same as the fuse that serves the right side blower that is working. One of the pins on each fuse should have a small resistance equal to the winding of the motor. The other pin on the fuse should be open because 12 volts is switched to it by the fan relay.

If it does have resistance then get the right side blower running and measure each side of the left side blower fuse (fuse removed) with a volt meter to ground. One side of the fuse should have 12 volts.

If you don't have resistance you will next need to pull the connector at the blower and use the OHM meter to check between the two wires going to the blower. If it is open you need new blower. If not open, use the Ohm meter to check the connector to the left blower. One wire should go back to the fuse and the other (brown wire) should have continuity to the negative side of the battery.

Jack D. (Southern Connecticut)
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