My KJ2 makes a slight whirring sound about 3 seconds after starting it, which lasts about 2 seconds before going away.

It only does this when it's been sitting overnight.

Any common issues that this could be?

I'm guessing ABS?

My TJ does that too. Either ABS waking up, or cruise control pump working?

I was initially thinking power steering pump? Or some bearings maybe from idler pulley etc?
It's only recently started making that noise

I was initially thinking power steering pump? Or some bearings maybe from idler pulley etc?
It's only recently started making that noise

Not idlers for exterior belts, I replaced both of these and it did not affect the noise.

One consolation, if it is a bearing, it will get louder and you will be in no doubt where the problem is. lol

this happened to my Ralliart, after about 2 weeks sitting its like you can hear it starving for fluids or something, then it passes and its fine. might be air in some lines of some sort :/

I have this too on cold start. Almost like a whining baby.

I think from memory it's either ABS or TCL performing a self check, I think it's actually detailed in the manual and our FG Falcon does the same thing (a self-check once the car begins moving or hits 20kph or something after being started)

I've had this noise for years. Never seems to have gotten any worse.