I bought an older H5 Honda Civic HB for track only racing and I need to wire a radiator control switch. I'm wondering what is the best way to wire it, such as power from the master electrical shut off switch or direct from the battery (what amp fuse should I run to protect it?, etc.)

I have a 10 Amp switch so I'm hoping that will be enough.

TIA

 

I think the radiator fan switch closes the ground side of the circuit, and triggers thru a relay anyway.

Meaning... your 10 A switch would be fine, & you just wire it in place of (or in parallel with) the existing fan switch.

 

I have to get a good look at the wiring but the fan does not turn on thus maybe the wires were disconnected or the relay has gone bad. I figured I'd hook up a nice toggle switch to turn the fan on when I'm going slow through the pits, idling or in case of a red flag session I can turn it on to keep the engine cool. However, once moving it isn't needed.

 

One easy way to wire the switch as an independent circuit would be with a single SPST (Single pole, Single Throw) relay and Utilize your factory (or aftermarket)Thermo switch (assuming it works 100% functionally)


*12V+ (10a Fuse) to Points 87 & 86

*Point 85 to one side of Thermo switch

*Point 30 to Fan Motor V+ side

*Fan Motor ground side and 2nd thermo switch wire to Chassis Ground

Hope this helps. If not ignore it haha.