My battery was not keeping a charge. I put a brand new battery in and the next dead car would not start. I jump started it and then checked it with a multi-meter and it was properly charged. Drove it around for awhile and all seemed fine. Two hours later car again would not start. Checked with multi-meter and only read 2.0. I jumped the car again and I bought and installed a new solenoid. Drove it around for awhile and when I came back home now the car would not shut off. I could even take the key out of the ignition and the car was still running. Any ideas why? A solenoid is pretty straightforward to replace. All connections were done properly. Would a bad solenoid cause this?