MyPretty99Pony

Hi. I purchased my '99 convertible 3.8L V6 5 speed about 2 1/2 yrs ago from a family friend. Had about 98K on it. No problems the first year other than I noticed some quirky things as I had it, like the windshield wipers would intermittently swipe across the windshield when the heat in the car was cranked up. But only once in a blue moon..was rare.

I took the car on a longer road trip, like 2.5 hours each way, used the cruise control on the way home,( if that matters)... noticed some odd things like the wipers and such. The next day I took the car to the store about 1 mile from my home. When I came out of the store, the car started but was VERY rough, stalled out, and when I started it again... it wouldn't turn over, tried a third time and two men came running over to me screaming to get out of the car because smoke was coming out of the hood. They opened the hood and the wiring in the front passenger side of the car was on fire. Near the passenger head lamp. They managed to snuff the fire out. Flames were about 6-8" high. Needless to say, I was freaked out. Towed the car to the dealer down the street and I called insurance company. Turned out the main wiring harness fried. The dealer found the last NEW factory harness in the USA and installed it. Insurance paid for it because they couldn't point any fault on me as the owner. The car still had all factory equipment installed like the radios cd player etc...( and after they had it a month), Car seemed fine when I got it back.

Now, fast forward until about 6 months ago, I started to notice that when I drove her, if I let the RPMs wind out in 1st and 2nd gear, my red battery light would flash on, but as soon as l backed off and drove her, normal/conservatively again, she was fine. I also noticed that the wipers started doing that odd swipe again. But again rare .....

Up until about a month ago, she was my "everyday" car. She was out almost every day. She sat for about 10-15 days in the garage and last Sunday, the weather finally was dry and nice enough I took her out for a spin. While on the road I noticed my interior dash lights getting dim.... and windshield wipers moved across the shield like a snail. Shortly after, the red battery light started flashing while I was driving, and so I turned around and headed back toward home. (but noticed when I sat at just an idle at a red light, all brightened up again and seemed normal) My gut said alternator, so I turned all electrical power sucking things off, dash lights, radio, heater fan, accessory charger....etc... as I headed home, the yellow ABS light came on, then the air bag light. I swear I lost power brakes because she felt like a train trying to stop. (but maybe my nerves were frazzled cause I was remembering my last electrical nightmare with her) I got her to the driveway and into the garage except last 18" or so and my little boy and I had to push her the rest of the way in. I had power for lights and "chimes" but not enough to turn it over to start.

My family friend who is also our mechanic came out and checked the battery. Battery was dated 2009..(ya think the dealer would have replaced the batter after a fire but guess not) He tested the battery and tried to charge it but the tester said "bad cells" replace battery. He got a brand new battery, hooked it up last night and when he started the engine, sparks were coming out of the wiring harness at the alternator.... So question is, replace alternator wiring harness??? and the Alternator??? or what BOTH? ANYTHING ELSE???

I read a lot of your posts here and I would really like your input here. I LOVE my Mustang, but I frankly afraid to drive her and don't need another problem. So I really would value your ideas and input. Any "known" issues, service bulletins, recalls, past experience???? HELP A GIRL OUT GUYS!!! THANKS FOR TAKING THE TIME TO READ ALL THIS.....

dawson1112

My first though when you said your battery light was coming on when you let the rpms come up was a slipping belt but, I suspect the dead cells in the battery were causing the alternator to work hard causing it to burn out.

Sparks from the harness are not a good sign , I would peel it back and make sure there are no melted wires in that harness. The dead cells in the battery can cause the wires to get hot because the alt,, was over working.

As for the windshield wiper thing, it could be a bad switch , or it could be associated with the battery/charging system issues, possibly even a dead short someplace in the harness.