cooling fan mod, spins slow

[Jim Hyman]

Brian, If your original cooling fan bypass switch is powered by the brown/white wire near the headlite wire harness, this wire is probably undersized and not able to handle the current needed by the cooling fan. The 'european' driving lite is only a 4 watt bulb (1/3 of an amp). The general consensus of past electrical posts is that the KLR's wiring harness is marginal at best. The brown/white wire is connected to a circuit that includes the instrument illumination lites, tail lite & license plate light. The combined electrical load for all these lights is about 2 amps. I haven't inspected all these wires (brown/white, red, red/blue, red/white) but i suspect that they can handle the load for the lites, but not for the fan. I couldn't find a spec for how much current the fan draws, but I would guess at least 2-4 amps (24-48 watts). Skip Faulkner recently had an excellent post regarding wire sizing to electrical loads. When you try to draw more power thru an undersized wire, voltage drops, electrical resistance in the wire rises, and the wire can overheat & melt. That's how a toaster works. We don't want to toast our wires! It was clever of you to use an available unused wire that would require minimal new wiring, but this is not a good way to go, due to the limitied electrical capacity of this circuit. The archives have several different approaches to wiring a manual fan switch. If you're going for the full over-ride** (bypassing the fan relay & fan switch), you'll need to splice into the large white wire "after" the radiator fuse: |fan| ==== |fan relay| ===+=== |fuse| ==== |battery| | | "+" | | new wire (#2) new wire (#1) The new wire (#1) will go to the manual switch & the other switch wire (#2) will go to the fan's blue wire. The manual switch also has to be able to handle the fan's electrial load. I'll see how much current my fan draws & post the info in a couple of days, unless Eric (just kidding!) or someone else posts the results first. Don't skimp on the switch, a cheap light weight one will not hold up in the long run. Remember, the white wire to the fuse is always powered, even when your bike is off. ** full over-ride will let you run your fan with the KLR ignition switch off (& also drain your battery when you park your bike & forget to turn the switch off!) Professor A9 Federal Way, Wa. [USA] ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ --- "Shepard,Brian" wrote:

> Actually I'm a little concerned about the fan switch mod

I did. As I said in my post, I hooked up the fan directly to the European Running lights leads. [snip] the fan doesn't turn as fast as it did. Before the mod, I could always hear the fan turn on over the noise of the engine. Now I can't hear it, but it is on and turning fast just not as fast as original connection. It is indeed working ...