My wife has a 97 Jeep Grand Cherokee and 2 nights ago when she was driving home from work the "check gages" light came on and the gages all dropped to zero. The car never seemed to lose power though. the last time this happened it was a bad alternator. This morning she got in and the same thing happened only this time the stereo went out, no power what so ever. I looked at the alternator and it indeed was bad. I replaced the alternator today and the wire from the alternator to the fuse box and everything powered on except the stereo. After I checked the alternator I had to jump the vehicle and someone put my car battery in backwards so I switched the connections with the jumper cables, accidentally put the positive from my car to the negative on her car and the negative from my car to the positive on her car. How much damage if any could this have caused? When this happened the horn, windshield wipers came on. Crazy but I hope it didn't mess up the Jeep.