It grounds when activated, aka it doesent send a voltage, correct?

 

JS0 itself is just a pin on the CPU. It is at +5 when active, and ground when inactive.

CPU pins, by themselves, are not able to source or sink very much current, however. In order to make it to anything useful, you'll need to connect a transistor to it, as is done with the relay driver modkit. If you use a PN2222 or similar, you'll then have an output which goes to ground when active.

 

I dont understand, Do I just do JS0 to Transistor to relay for the water injection? Or is there more involved in the circut

 

Are you trying to build the WI circuit? or are you trying to just activate a WI pump?

For the latter you just need a simple transistor circuit as Joe describes. For the former you need to build the WI circuit as described in the Megamanual

 

MS-Extra Manual Index

 

I dont get it, to me it seems the diode is the wrong way, when the transistor opens, it will alow current to pass the relay and flow through the diode? Shouldent the diode be the other way?

 

When an inductive device which has been passing DC is shut off, the electromagnetic field within it collapses back into the winding, inducing a large voltage spike in the reverse direction. In the case of an ignition coil, this is a good thing as it drives the spark plug. In the case of a solenoid or a relay, this is generally undesirable.

The diode is there to provide a bypass across the device, to essentially short-circuit this spike and prevent it from propagating outwards.

 

Thanks for that. Do you think transistor p/n ZTX450-ND would work? Just google the p/n.

 

The ZTX450 is rated at 1A. More than enough for 2 or 3 relais even.

 

ok, sweet. Ill beable to make the circut with spare parts.

 

nothing special about the circuits, same as the fan switch and boost control.