Frank is looking for a way to tell if the fan is actually running, not just if it's getting power. I may be way off on this, but the only way I can really think of, is if you use a two speed fan, it seems to me that which ever speed is not in use should be acting like a generator? Before I had a relay on my fan, I just had it wired straight to a switch that lit up. Going down the highway with the fan off, the air traveling through the radiator would spin the fan fast enough for it to generate power and light up the switch..
Yeah, I can't think of a way to make a light indicate whether the fan is actually spinning. But if it grounds out the fuse should blow, so that setup will basically tell you everything but that.
if the power wire comes loose on the fan, the light will still have power and a ground. it will still be lit and the fan will be off... if there was a way to put a light on the fan...the factory...would have done it... ...Frank...:Handshake
You could always wire the light directly to the hot and ground wires on the fan instead of to the relay. That way you'll at least know if something happens to any of the circuit going to the fan. Or maybe the answer is to rig a warning light for engine temp instead, like the manufacturers do it. Or how about this... One would think in most cases, (not all, unfortunately) that if the fan motor goes out it would break the connection between it and say its ground wire, right? So you could put a relay in line with the ground (or hot) going to the fan, and use that to either activate or deactivate a light.
you could put a amp gage in the power wire to the fan. it will show you if the fan is working or not.
"Going down the highway with the fan off, the air traveling through the radiator would spin the fan fast enough for it to generate power and light up the switch." would this factor into the amp reading? ...Frank...
If you are using a relay inthe wiring of your fan (and you should) no power will be generated unless the relay is energized - then it would be turning under power - not generating power.
personally... if you drive the car on the street just get a flex fan... if it is a weekend car or you run it at the track electric all the way! back in the day for the hell of it we took off the flex fan at the track and ran the car without it. it ran consitantly two 10ths faster! not just one time not two but every time we ran the car that whole day! enough said. now this doesn't mean if you have a 9 sec car you will gain two tenths... but if your car is a 14 or 15 sec car it probably will.