Ferrino
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| posted on 27/3/06 at 02:53 PM |
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Switching Rad Fan
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]
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David Jenkins
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| posted on 27/3/06 at 02:59 PM |
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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
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Peteff
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| posted on 27/3/06 at 03:47 PM |
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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.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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BKLOCO
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| posted on 27/3/06 at 03:57 PM |
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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.
Experience is what you get when you don't get what you want!!! 
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nick205
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| posted on 27/3/06 at 04:15 PM |
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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.
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Ferrino
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| posted on 27/3/06 at 04:38 PM |
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Thanks guys, I think I will stick a relay down by the rad. Does the following quick-n-dirty diagram look about right?
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speed8
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| posted on 27/3/06 at 05:07 PM |
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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.
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jimgiblett
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| posted on 27/3/06 at 05:58 PM |
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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]
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speed8
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| posted on 27/3/06 at 06:08 PM |
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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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jimgiblett
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 posted on 27/3/06 at 08:10 PM |
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quote:
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.
Oops yes should have read your diagram first
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Ferrino
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| posted on 27/3/06 at 08:43 PM |
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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.
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jimgiblett
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| posted on 28/3/06 at 08:25 AM |
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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
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Ferrino
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| posted on 28/3/06 at 09:47 AM |
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Will do - cheers!
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