Pulsating steering - not the discs.

[jammy]

'99 Grand Prix GT

When I'm driving and not braking, and I apply slight pressure on the steering wheel to turn on a curved road, I feel a very slight and subtle pulsation in the steering wheel. There is no pulsation when I brake, or when turning the wheel when the car is stopped (e.g. turning at a stop sign.)

What's the cause of this? Is it something to do with the power steering pump?

TIA

[FordMan77]

Probably a worn hub bearing or an axle.

[jammy]

Probably a worn hub bearing or an axle.

Would I be able to tell by jacking up the front and checking play in the wheels? Would there be any way from the pulsation to tell which side may be affected?