Fitting Spec C Intercooler spray to a 'dry' classic

Discussion in 'Projects, modifications & how to guides' started by ASJ, Mar 30, 2011.

  1. Bruce McArthur

    Bruce McArthur V-Limited Member

    Thank you - It would help to know what the factory setup does...
  2. Bruce McArthur

    Bruce McArthur V-Limited Member

    OK - Electrical experts ahoy

    I've assembled the Jaycar KA1732 timer circuit but the instructions of operation are written by a boffin for boffins (I'm not a boffin) - so I need help understanding the outputs of the relay, of which there are 2 that operate simultaneously.
    with 3 pins per output, NC1, COM1 & NO1 (see diagram below) + NC2, COM2 & NO2

    I need to figure out which pins do what to run the IC Spray pump - no factory wiring as I am adding this where there was no sprayer originally. I guess 12v power goes to one, vehicle earth another ?

    I guess I could use output 2 to operate an LED or the back lighting of the factory IC Spray button ?

    Help appreciated..

    Attached Files:

    Last edited: Aug 9, 2019
  3. Mad Max

    Mad Max V-Limited Member

    NC is Normally Closed, and NO is Normally open on the relay, Com is the common wire. This is the state of the relay when no power is fed to it.
    Power to the relay is the 2 pins on the left (the coil looking part) with a diode for protection.
    When power is NOT there the common is connected to the NC part on each switched side.
    When power is applied to the coil, it switches the common over to the NO part

    Sadly the diagram doesnt have pin numbers on it for the relay....

    So yes you could have on feeding the spray and one indicating an LED

    Hope that is of some help?
  4. Bruce McArthur

    Bruce McArthur V-Limited Member

    Kinda - call me thick , but I really don't understand fully - I need to know if the output from the relay is to power the pump directly, and if so what connection supplies the power (COM1, NO1 or NC1 ?) and what one do I connect the earth return from the pump to ??
  5. Mad Max

    Mad Max V-Limited Member

    No worries! :)

    I dont know what the relay is rated to, but would imagine the pump doesnt use that much power.
    COM1 will need to be a 12v supply from somewhere (I dont know without looking at a wiring diagram for the car where the pump normally draws power), Cigarette lighter is usually a favourite though, as its a higher rated supply.
    NO1 will be connected to the pump
    NC1 will not be used

    The earth for the pump does not need to connect to the relay.
    Find an earth point on the body near where the pump is will be easier
  6. Bruce McArthur

    Bruce McArthur V-Limited Member

    Thanks so much for your reply and guidance...that will help me get it tested before I fit it. ;-)
    • Like Like x 1
  7. Mad Max

    Mad Max V-Limited Member

    Happy to help!
  8. Bruce McArthur

    Bruce McArthur V-Limited Member

    Just tested it and works great...momentary IC Spray switch will trigger the circuit for a burst of the sprayer motor for a selectable time period (7 sec, 12 sec, 25 sec, etc). For my rally car I think I can have the microtech ECU use one of its 2 AUX outputs to trigger at a desired air intake setting so the whole thing becomes automatic but can also wire in a momentary switch to manually activate it as well.

    Just got to add some PCB mount screw terminals to the board to make the wiring easier and job done.
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