Hi Kevin and the gang, newbie here, first post. Just bought a 08 xt660r took it out for first ride yesterday, ran really well but when in traffic in Aberdeen the over heating light came on the dash (plenty of coolant in tank) cooling fan wasn't cutting in. As soon as I got on dual carriage way and got some speed up overheating light went out. Read the forum for suggestions and went on the diognostics. The diognostics had four error codes logged, 12, 14, 21 and 30 and diognostics no 9 which is the voltage is reading 0.0 instead of 12 volt. I have connected a desperate battery up to the cooling fan and the fan works fine. I have tried activation code 51 and the fan dosnt come on.
I have cleared the codes from the memory and ran the bike on tick over for a while and the overheating light still comes on and the fan doesn't work, any suggestions would be gratefully received. Sorry for the long post. Thanks Alastair

Welcome to XT660.com Alastair.

I don't think any of the stored codes you had were/are necessarily anything to do with your current problem? Although 21 is the coolant temperature sensor. If it was still malfunctioning though the bike probably wouldn't run right (as the signal to the ECU is fixed at 80C) and the engine trouble light would be on.

Not sure why your fuel injection system voltage is 0? The bike wouldn't run if that was the case and if below 12V and running the engine trouble light would be on?

If you know the fan is good, and the engine trouble light isn't showing (at the moment), then you can rule out the fan, the coolant temperature sensor and any fault with the ECU (as the last two would throw up the engine trouble light).

It is perhaps most likely something to do with the wiring, the fan's fuse or it's relay, as all these things will cause the fan not to work and overheating, but give no engine trouble light or error code - just the temperature warning light.

Have a look at the following:

1) Check the fan's fuse
2) Check the connections on the fan relay are good
3) Check all the wiring in the fan circuit for abrasion/corrosion
4) Run the D51 test (which checks the fan relay) and listen to see if the relay clicks

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Hi Pleiades thanks very much for your reply I had already done test 51 without success, the connector under the tank was a bit crappy and the fuses in the fuse box were marked the wrong way round, once I had found the right fuse it was actually blown so due to your help its all working again. Done test 51 works fine. Only thing now is what did the fuse blow in the first place. Hopefully it will keep running and hopefully no damage to engine. Many thanks Alastair

Carefully check over all the wiring looking for one that has perhaps worn through to the core which could be causing an intermittent short.

It could just have been a dicky fuse, or perhaps dirty fuse contacts causing high resistance/heat build up in the holder which in turn is conducted to the fuse wire eventually melting it?

Fingers crossed it stays working for you...

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