I
do not recommend this wiring circuit to be used for controlling an electric fan since it has no temp sensing capabilities. The circuit is presented merely as an illustration on how to wire an electric fan. It is functional and will work, but does not turn off or on in response to coolant temps. That means you can overheat the engine or run the battery down very easily.
If your Bosch relay is SPDT, one set of contacts is closed then the fan is on. The other set of contacts is open when the fan is on. When the fan is off the set of contacts that were formally off are now on. Wire the indicator to that set of contacts.
Wire sizes:
Fan power feed & Fan ground 10 gauge stranded wire.
Fan controls, relay & LED's 18 gauge stranded wire.
Surge Dampner Diode: 1N4003
Fuse: 30 Amp automotive or circuit breaker
LED's
Green: Radio Shack #276-271
Red: Radio Shack #276-271
No external resistor is needed, since the LED's are designed to run on 12 volts.
See
http://www.fordmuscle.com/archives/2003/02/electricfan/index.shtml for the best way to cheaply control an electric fan. Advance Auto Parts or AutoZone will have the Hayden controllers. One is $30 and the other is $50.
The DC Control (
www.dccontrol.com) is the best on the market unless you have electronic skills and can build your own. It is expensive $108+ shipping and may have an extended wait time for delivery.