Turn brown/dead grass green again?

This specialist website will be of help to you with more advice on that.

http://www.gardenguides.com/86254-revive-lawn.html

I have the same problem, and with the heat and our drought, this is happening all over Southern California. Only lots more water and fertilizer will cure the problem. Although you may have to dig up or root out the really dead stuff. But usually, watering not to often, but longer so the grass roots get a good soaking will cure that browning.

Check your water bill, and see what your allowance is, and if you can water more, or just wait, until the cooler weather comes back.

Stop washing the car on the yard. It's fine, if you are just hosing the dirt off, but not when you are soaping the car. I'm sure that soapy water, isn't good for your grass.

Not to repeat John and Graham, first you need to remove the dead and brown grass as that stuff won't come back to life. It's dead. so rake, mow and aerate your lawn, removing all dead grass and grass parts. Add some lawn fetilizer. Then water the lawn to its soaking limits. You may have to wait until October or November to do this, when rain in your area will be more common...maybe.

SoCal is a hard place to grow grass. If you live in the Mohave desert grass does not grow naturally there. People there who have green grass have expensive underground watering systems. Their water bills are perhaps very high, too.

Washing cars on a lawn is a complete no no. Detergents contain all sorts of stuff that will kill grass, including salt. Watering lawns is best done when it's cool[calif?] and use plenty of water, approx 2" of water. If your unsure how much 2" water is, place a cup in the middle of the lawn when the sprinkler is on, then you can measure it. You'll be quite surprised how long there on for! never give little and often, as this brings the roots up to the surface and then they scorch in the sun.

Cut the grass as short as poss, then scarify it, then seed it with a light coating of soil. Or re-lay it.

depends on the type of grass. some grass like winter rye will dye off in the summer and come back in the fall. but most likely just water what you have and if it dont grow back then just reseed it