2000 Chevrolet Impala

Electrical problem
2000 Chevy Impala 6 cyl Front Wheel Drive Automatic 150000 miles

For the past few weeks, everytime I hit the brakes and turn signal (more left signal than right) the car makes a whining noise and the brake light and battery light come on in the instrument panel. I have had the local mechanic hook it up to their computer and they found nothing wrong. Today as I was driving home, the windshield wipers would go up an inch or two and back down, while the windshield wiper control was in the off position. I pulled off the road, looked under the hood, shut the car off and turned it back on. This fixed the problem for now, but I know it will be back again. A couple of months ago I had the wiper blade motor replaced. My husband thinks there may be something wrong with the electrical board or computer chip. This sounds bad, any other suggestions?
June 2, 2008.

Check if any rewiring was done at the time the motor was replaced
also I would check the charging system and multifunction switch

Multifunction switch : controls turn signals, headlights high /low beam, wiper/washer and cruise control if equipped

also check for any codes in the BCM

Jun 2, 2008.
One more thing, sometimes when I put the car in park, the engine seems to idle higher than when it was was in drive. Any suggestions? I hope my little car isn't going to blow up on me! : )

Jun 2, 2008.
Its very possible to be with in the normal range for it to idle a bit higher in park and or neutral
that because no tranny torque
if its under 900rpm I would say its normal
you may also check for vacuum leaks
but that again will or may set a check engine light on with a code

Jun 3, 2008.