I'm using the rad fan from the R1, which is normally switched on by the thermo switch in the rad. I would like to add a manual override switch on my dashboard (the ones I have are rated 16A) and was wondering if I should use this switch to operate a relay instead of switching directly?

The fan fuse on the bike is 7.5A, so I'm guessing that load is fine for a 16A switch to carry, or am I missing something (maybe related to the relatively long run from dashboard to rad at the front)? Think I'm just confused 'cos most 7s seem to use a relay to switch the fan, but these bike fans are pretty small I guess.....

Thanks

[Edited on 27/3/06 by Ferrino]

Personally, I would use a relay with anything that has a motor in it - it's not just the running current, it's the start-up surge and the switch-off arcing, that eventually screws up switches.

Unless you put a big, fat switch on your dash, that is. If you're fitting a light-weight decorative switch then a relay may be a good idea.

DJ

Fit a switch on the dash which bridges the radiator switch, that would do the job. If the fan runs on a 7.5 amp fuse your 16 amp switch should be alright.

Is the switch rated 16A ac or dc if its ac then the dc rating will be a lot lower.
I would use a relay personally as the back emf from an inductive load could easily burn the switch contacts and cause high resistance which will cause the switch to overheat and ultimately fail.

use a relay, then you know the switch will be Ok in the long term and you won't be back reppeating the job a short time down the line.

Thanks guys, I think I will stick a relay down by the rad. Does the following quick-n-dirty diagram look about right?

As far as I can see from the wiring diagram you could just take a feed from the wire to the ECU and switch it to ground.

Like this.



fan bypass

If this is wrong can somebody tell me cause this is how I'm planning on doing it.

No need for a relay just use the existing ECU fan controller

If 98-01 model by taking the green/black to earth


9801 Fan Overide


for 02-03 model by taking the green/yellow to earth



0203 Fan Overide

- Jim



[Edited on 27/3/06 by jimgiblett]

That's what I was trying to show with my amateur drawing. My switch is coming off the Gr/Y wire to the ECU.

quote:

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Originally posted by speed8
That's what I was trying to show with my amateur drawing. My switch is coming off the Gr/Y wire to the ECU.

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Thanks guys, but my engine & rad are from a '99 R1, and unless I am mistaken (quite likely!), there is no fan relay or ECU control - the power just goes straight from the fuse and into the thermo switch (which lives inside the radiator) and then onto the fan motor.

Just had a look at the wiring diagram and you are right (no relay just a thermo switch). Thus I'd agree with others and put in a relay.

- Jim

Will do - cheers!