I have been thinking about different setups for fan control as I have changed mine around a number of times...

it dawned on me that (for my setup) a speed sensitive control would be excellent, so that the fan would shut off (or nearly off) at speed, and fire back up at a stop light.

Well after racking my brain with thoughts of how to use the speedo 's electric signal, the powersteering system dawned on me.

Anyways - my point is - could the variable assist power steering (on an S4) be........somehow.........used to control the fan this way?

1. Does *some wire* on the p/s become live when you are stopped, or under a certain speed?
2. Is there enough room on its circuit to allow the load that the low side of a relay wold draw?
3. Are the wire (or wires) in question simply on/off, or are they a constantly varying voltage?

It was just a thought and if it could be done I'd certainly use that setup.

Any input is greatly appreciated.

 

I have not done it electrically, but Toyota/Lexus does a simular set up except they use a fluid propelled fan, that is looped with the power steering fluid.

So in therory that would work.

Electrically, I would have to play around and see if the output of the power steering CPU is strong enough to activate a relay or needs a transistor.

Usually the easist way, is just to hook a relay up to the "over the top" switch, that when the car is in 5th, it disconnects the fan for reduced electrical load at freeway speeds.

 

hmmm and which little device on the tranny would the "over the top" switch be controlled by?

 

Over the top switch, is just what Mazda calls the 5th gear switch. Its used by the ECU for emissions control and on the S4 models to turn off the shift up light

 

hmm, well I dunno.....

Ill maybe have to do some driving around with the multi meter temporarily wired up under the hood and see which wires have power and what kind of amps they have...

The 5th gear switch sounds like a good plan, but what would happen when im doing 60-70km/hr in 4th? I guess I don't need the fan then anyways.....hmm i dunno.....

Do you know off the top of your head which wire on the P/S motor is powered when at low speeds? if not Ill check the FSM and try to decipher.........