The power to my '97 Chevy Lumina quits when using brakes only sometimes.

check grounds check battery cable to see if they are loose and check ground connection at back of engine on trans bell housing and one more i would check the ground on the brake pedal bracket for loose connections if u need u a pic to know what to look for let me know

Along with checking the grounds, clean/check the positive electrical connections at the battery, starter and alternator. When you step on the brakes, extra load is put on the battery to light the brake lights. At the same time, the engine fuel is cut off and engine moves on the mounts. Since the radio and speedometer quit, it sounds like you lost all 12 volt power. Checking your grounds is a good place to start and you should have one ground wire to the engine block and another ground wire to the frame.

Check your vacuum, i saw this problem three times before, once on my own car..... when you apply the brakes, the booster "sucks", then the vacuum drops dramatically, due a crack in a hose somewhere..... and so your engine stalls..... often a vac leak won't be in your face.....it could be, and often is, a crack at where it attaches to a fitting... and then, when vacuum increases or fluctuates, whatever, the crack opens and the vacuum drops... then the crack seals again... temperature can also effect a crack in a vac line.... anyway, check ALL your vac lines for leaks, or just start replacing them if they look dry cracked.... there are also thin plastic vac lines that crack... some are hidden within that spiral looking black flexible conduit.... especially look around where your cruise control solenoid is, and your map sensor..... there might also be a line going into the front drivers side fender to a big ball, called a vacuum reservoir.... it maintains vacuum when you turn on your HVAC controls and such..... you can borrow a MityVac tool from Autozone to test your vacuum..... at idle it should read anywhere from 17-22..... it'll probably read about 19.... the manual will tell you how to read the guage..... a Haynes manual will also tell you what the various readings mean..... it's a fun tool and can tell you a lot about the health of your engine..... Good Luck and Happy Holidays!

Thank you all who answered, I also had someone tell me that it could be a vacuum leak or hose leak, so I have a few different things to test now. I have driven my car about 70 miles since I unplugged the torque converter wire and it hasn't stalled or done anything weird thus far. However, there are days where it doesn't do it at all and days where it runs perfectly smooth. Would a vacuum leak also explain the fact that the car has stalled when applying the breaks when it is in park?

Yes! Even in "Park". As soon as you start your engine, a vacuum is created... think of your engine as an internal combustion vacuum cleaner... and the part that "sucks" like a vacuum cleaner is your throttle body... when your engine is running, you will always have a vacuum.... If you your car uses a device that operates on a vacuum, and that device is bad, has a leak, or the hose going to it has a leak... your car will stumble and/or stall..... HVAC Controls are often operated by a Vacuum system..... my car's HVAC controls stopped working once..... had a bad/cracked hose near the cruise control solenoid.... replaced it..... tadah! .....bad VACUUM can be an indication of several different problems..... again, it can be a good diagnostic tool, and can even be used, with a vacuum guage on your dash, to improve your fuel mileage. They used to sell them in the 50's for such a purpose..... it was called a Mile-O-Meter... I have one on my dash from 1951! ----- my car is a '90 Lumina V6/3.1 Euro Coupe..... just about every vac hose and fitting has been replaced.... rubber and plastic on cars rots and gets brittle over time.... http://www.classictruckshop.com/clubs/earlyburbs/projects/vac/uum.ht m ----- http://www.gregsengine.com/using-a-vacuum-gauge.html ----- http://www.secondchancegarage.com/public/186.cfm ----- http://www.international-auto.com/fiat-lancia-tips-on-reading- gauges/tips-on-reading-gauges-vacuum-gauges.cfm -----

thank you 90v6redhot! i brought my car to a mechanic on saturday and he didnt mention anything about the vacuums or hoses, i will probably bring it back to him and have them check those!

It's rare to see a "today" mechanic whip out a Vac guage. I've never seen any mechanic do it (30 years amateur mechanic). I guess it's mostly an ol' timey mechanic thing. I learned how useful it was when I got that cool antique Mile-O-Meter off Ebay...... short story: was a car salesman for about a month (too bloodthirsty a biz for me), but, lady came in, wanted to trade in car, told me why, stalled at stops, stalled a lot.... mid 80s T-bird V8, went out to see her car, sure enough, large vac line behind carb to brake booster.....Hissing bad, had a piece of vac line in my van, fixed her car, she left, my boss coming thru the lot, i told her i had to go to mens room real bad, she left, boss came up to me, asked what happened (they don't like people leaving), told him lady felt very sick, i walked her out to her car, said she'd be back...... left biz soon afterward.....

Thanks everyone, but we finally found the cause of my cars problems. A major wire that runs through the car was so weak that it broke in half when we were looking at the wiring. A wiring problem makes sense because the car was very random when it would have the problem. Thanks again!

How do u no if u got a blown head gasket