I was driving and instrument panel flickered on and off a couple of times then stayed off. Also now battery, about 1 year old, doesn't stay charged. Would it be short in wiring? Or what?

 

Sounds like possible alternator. But it could be anything from a loose connector to relays fuses etc. You must mean you have a 2002 lexus sc430

 

Where do I start for troubleshooting? Where can I get a wiring diagram? Yes it is 2002

 

Wiring diagram book can be purchased on eBay.
It sounds like your car is the problem but You could get your battery checked at Autozone etc.
How long does your car need to sit before the battery is dead?
As for dash, do you mean the dash lights flicker on and off at night and now they just stay off?

 

Battery about 1 1/2 years old. This issue started late in fall and I live in Minnesota do stored it. Now that spring is coming want to get fixed. Battery drain in a day

 

Not just the lights but totally out so can't see how fast I am going, odometer, etc. while driving went off/on about 3 times and then totally off within about 5 minutes.

 

Seems odd that dash lights would cause a battery to go dead when the car is just sitting.
Mr.B had a good suggestion to check the alternator. You could take it off and have it bench checked.

 

...so are saying that the lights went off in about 5 minutes or the whole car went off ? I was thinking the alternator also, but if only the dash lights went out & he's still able to drive,could it be something else? When my alternator went out, all my lights on the dash CAME ON, before the dash blacked out & the car died.....

 

If it does turnout to be your alternator and you are a DIY person, I highly recommend doing it right.
Remember, Autozone rebuilt alternators etc. only replace the bad parts and not everything.

This website allows you to rebuild the alternator yourself.
http://www.aspwholesale.com

 

Here are a few items for you to do before jumping head first into replacing parts:

> Insert an ammeter between the battery and the rest of the vehicle. Wait for a little while for the instruments to settle out and then measure the current draw. If it is more than 200 mA, you likely have a short somewhere. (It actually should be quite a bit lower than that.)
> Have your battery load tested. It is likely toast by now. Auto parts stores usually do this for free.
> Have your alternator tested.

Let us know what you find out. Good luck.

BTW, welcome to the forum.