Logic mosfet to switch 12v truck battery
You're on the right track, and a MOSFET could be used.

The gate-to-source voltage (Vgs) must be greater than a threshold specified by the datasheet to conduct from Drain-to-Source (assuming you are using a N-Channel MOSFET). This threshold will be listed as Vgs(th).

Below, the N-Channel MOSFET is shown to be controlling the high-side of R (your load, in this case the 'steering wheel'). This is based on your drawing, which shows a N-Channel MOSFET, with current flowing to the steering column, Drain-to-Source.







simulate this circuit &ndash; Schematic created using CircuitLab

This could work, but the voltage applied to the gate would have to exceed the threshold voltage added to the voltage drop across R:

Vg > Vgs(th) + I(R)

In your case, Vg is supplied by the Arduino. Having a N-Channel MOSFET on the high side will likely not work.

Solution:

While you could use a P-Channel MOSFET on the high side, it is much easier to use a N-Channel MOSFET on the low side, shown below:







simulate this circuit

Your required gate voltage formula now becomes:

Vg > Vgs(th)

Alternatively, you could also use a solid state relay.