Like I don´t have any info about this system, I´ve removed trunk panels and study the complete wiring.....here are the wire colours :
Black : conected to ground
Brown : conected to terminal "85" of relay.
Brown (85) : to pressure sensor
Red (86) : to (+)
Green (87) : to water pumps
Red (30) : bridge to red (86)
At the right of the power steering reservoir it´s located a inlet manifold presure sensor....(looks like an oil pressure bulb)
When a high pressure it´s measured, thia sensor "close" the circuit sending a ground signal to a relay, activating it (located over de fuse box), this relay sends 12V to two electrical water pumps (are like windscreen washer pumps, manufactured by Hella). This pumps sends a good quentity of water to a nozzle that is located in front of air intecooler....
A very good purge is needed to get water by the nozzle.
A easy way to test the system is disconnecting the brown and the black wires of the sensor and joining them.
For more info go to : http://digilander.iol.it/hfalex/index2.htm
click in "tech info", and then in "water spray kit".
1 : Water tank
2: Water Pumps
6: One way water valve (manufac. by hella)
21 : Sensor bracket
Sorry about my poor english.
If anyone needs something plz don´t hesitate send me a email.
Sebastian (´94 Q4)