So my X5 had the standard aux fan failure. After reading the failures of some cheaper OEM copies and the ridiculous price BMW charge for the OEM part, I looked for an easier (and cheaper solution).
With stand alone ECUs, most use a PWM output to modulate different electrical components and this is exactly what the signal wire for the X5 aux fan is. It is simply a PWM signal wire. The other two wires are power (constant) and an earth.
As with standalone ECUs, a Solid State Relay (SSR) is used to control any normal 12v motor by the PWM signal wire.
So I simply wired up a SSR to the X5 and fitted a normal 16inch thermo fan to the front of the radiator.
It works perfect, just like the OEM and total cost was about $40 for the SSR and $250 for a quality thermo fan.
SSR in Australia
https://www.jaycar.com.au/solid-stat...ching/p/SY4086
This is how I wired it up
If you were to do it though, you will probably need a 15inch thermo, the 16 was a little big to fit flat against the radiator (I got creative)
10-25-2016, 08:19 PM
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