Wilsons Sandbox

On Fri, 30 Apr 2004, George Sinchent Quinby Adams wrote:

> Why does it need a relay, and what does a relay really do?

A relay allows taking a small current, like from a temperature sensor, and use it to switch a bigger current, like a fan motor. You can go down to Radio Shack and look at transparent ones to see how that works. The small current goes through a wire wrapped around a piece of iron. When current flows, the iron becomes magnetized, and pulls down a flexible piece of metal (hooked to the fusebox and thus to the battery) to touch a contact (hooked to the fan). When the flexible piece meets the contact, current flows, turning on the fan. The usual failure mode for a relay is that either one of the wires to foil or contact go bad, or the contact burns off due to fluctuating current in the magnet (such as might happen with a bad sensor) causing it to repeatedly arc. You can replace a relay either with the specific relay or with a generic one. When the horn relay went out on my mother's 1982 Honda Civic, Honda wanted $50 for a new one. I went down to Radio Shack, bought a generic 12 volt relay for $5, wired it in and RTV'ed the thing to keep water out of it, and it worked fine until she dumped the Civic in 1992. The advantage of an automotive-quality relay is that it's typically more robust than a Radio Shack quality relay. Also note that you have to do some current matching here -- a relay that requires more current to activate its coil than is put out by the temperature sensor is going to burn out the temperature sensor. So while that horn relay was fine for what I did with it, you probably want to at least put an automotive quality relay with the right current rating for this application, if you don't put the "real" (official Kawasaki) relay on there. -E

Eeny meeny miney mo....um A13...hey I'm catching on (even if I had to use my fingers to count) In other words, in laymans terms mine is a '99 Hopefully this weekend I'll have time to get to the bottom of this (and maybe to the bottom of a brew or two)

--- In DSN_klr650@yahoogroups.com, "hijklr" wrote: > George, > What year is your KLR? A dealer had to replace the thermo > fan switch and relay on my A17 under warranty at 5800 miles > because the fan quit. They lost (denied ever seeing it) the KLR > harness for the wolfman tankbag. I was able to get the fan > spinning by grounding the switch lead but dealer said they > couldn't. Half the pleasure of owning a KLR is being able to > work on it with the help of others. May the KLR live. > Kevin