12v source only when engine is runnig(L300)

[gura119]

I don't know if this is a stupid question, but I really don't know about this .

Is there any way to have a 12v power source only when engine is running guys?

Mine is a L300 Diesel

[Overlanderjay]

Sure but you need to know how many AMPs you want to draw .

[gura119]

Thanks for the reply bro

not a big current, I just want to run a relay from it.

[Overlanderjay]

Then yep its possible the easiest place to tap in for power is under the dash where the steering column is, the key switch wires are there your looking for the black wire with the white stripe it only powers on when the engine is running and off in the accessary position . Cheers jay

[gura119]

Doesn't that wire power it self when key is "on" position and engine is off?

[Overlanderjay]

Yep

[Growlerbearnz]

I think he means when the engine is *running*, IE spinning, not just when the key is in the Ignition position. A power source that would cut out if, for example, the engine stalled.

Some older alternators used to have this, but I've not seen it for a while. Some motorbikes have something similar on the headlamp (DRL) circuit which latches when the starter is operated, but it doesn't disengage until the key is turned off, and it doesn't care if the starter doesn't actually start the bike.

You could put a SPDT relay coil across the oil pressure light, and run [unnamed widget] through the Normally Closed contacts of that relay. If the oil light is on, the relay is also energised, which opens the contacts and disconnects power from [unnamed widget]. Once the engine is running, the oil light turns off and the relay coil shuts off, reconnecting [unnamed widget]. Obviously you'd get [unnamed widget] power from the ignition (not ACC) switch, so it could only run if the ignition was turned on *and* the oil light unlit.