Oil Pressure Light

Your actual oil pressure is hovering at the danger level of say 5 psi; get it checked with an actual mechanical gauge before you start hearing a banging sound from the engine, because by then, it will be too late to save the engine.

You don't say you've checked, so I'll ask: have you checked your oil level?

There's probably a less-than-5% chance of that being the actual cause. More than likely, the oil pressure switch (that lights the dash light) needs replacing - very common phenomenon on Chrysler vehicles (although the OP did not specify the vehicle). Would not be unusual for the switch to also be dripping oil, as internal leaking is often the failure mechanism that throws the switch trip point out of calibration - but external leaking doesn't necessarily accompany the internal leaking - initially anyway).

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

That's what I think too. I think you have about 4 psi at idle, and/or maybe you're a couple of quarts low.

Had it checked and it was fine

Had it checked and it was fine-It only comes on when I apply the brake

I agree with the others to have your oil pressure checked (with a mechanical gage). But I doubt if the problem is truly low oil pressure (but you don't want to assume that and damage your engine).

On a properly operating engine, your oil pressure will be at its absolute lowest when running when the engine is at operating temperature, idling, in gear, and vehicle stopped. With a good oil pressure switch, this will be above the trip point of the switch with some margin. If the pressure switch is out of calibration (due to an internal leak), then normal idle may not trigger it (the pressure would be just above the incorrect trip point with no margin), but if the idle drops just a tad below normal (SAY, WHEN THERE IS A VACUUM CHANGE DUE TO APPLYING THE BRAKES), then it will trip the switch and light the dash light.

If you are traveling down the road in gear, does the light come on? Or is it only when you are stopped, in gear, with the brakes on? If the pressure switch is bad, the latter will be the case.

My advice: Get the pressure checked as others suggested, and while they have the switch out to temporarily hook up the mechanical gage, heve them put in a new switch - OEM only - not aftermarket. The switch itself will cost less than $30.

My full expectation if you do that is that (1) You will verify that your pressure is in spec., and (2) The light problem will be gone.

Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')

You're either a) low on oil, or b) the oil pick-up screen is too high above the bottom of the oil pan. Is the botto of your oil pan dented inward, by any chance?

HAD it checked? Check it yourself and be sure!