My 99 Sonata had not been having problems. Last night on my way home, I stopped and when I tried to start it, it was dead. I called for a tow and the driver was able to get the car jump started. When I turned on the headlights, the car died again. He was able to get it started again and I had a new battery put in. Now it starts fine but whenever I start the car, the doors lock and when I turn the car off, the driver's door unlocks. My door remotes are not working. Is this a sign of electrical problems to come? I am going to set up something with the dealer to have it worked on but I want to know what to expect. Has anyone else had a similar problem? Input would be greatly appreciated.

 

the alarm system in that car is pretty old. the dealer really doesn't do much with that system in terms of diagnosing it or fixing it. what they might recommend that you do is remove the alarm system from the car if they can't reprogram your remotes to work. shouldn't be anything crazy though.

 

I have no experience diagnosing the lock system, but I suggest you have the alternator checked out. Once the car had started from the first jump, the alternator should have been able to supply enough electricity to keep the car running even with the lights turned on. I suspect it's not supplying the ampage it was designed to put out.

 

It actually doesn't have an alarm system. It has been starting and powering fine since the new battery. The alternator light hasnot come on at all. The car was competely dead when I tried to start it. I didn't even have interior lights, or dashboard lights. I noticed today that the clock in the car will not even reset. Seems like there may be something odd electrical going on. It looks like it is going to have to go to the dealer. Maybe it is time to take a look at a new Sonata. Thanks for your help.

 

I'm not familiar with the 99 Sonata, but I'm guessing it has an idiot light like my 08 Sonata, 95 Taurus and 93 Maxima. I've lost two alternators in 15 years. My experience is the idiot light doesn't come on until zero amperage or total failure. My Nissan once drove me crazy for about 6 months because it exhibited similar starting problems as your Sonata. I tested and replaced the battery. The car would run about three days and then start acting up. Putting a battery charger on the car overnight would fix most of the problems. The alternate idiot light never came on. I had the alternator tested tested at a national parts store, which said the alternator was OK. I final took the car to a mechanic who sent the alternator to a specialty alternator shop that found the problem. The Nissan had a Hitachi altenator with a failing diode that was temperature sensitive. Cold it would deliver nearly full amperage, but only had to warm up a 10-15 minutes under load before the amperage would drop off to about 10% of normal under full load. Apparently there was enough electricity being generated to keep the idiot light off, but not keep up with the demand of the car. I still suggest you have the dealer or a specialty shop check out the alternator.

This mechanic also suggested a procedure to me that has often worked to help "reset" some eratic electrical problems. Disconnect the battery from the car, starting with the ground (negative) lead first and then the positive lead. Then walk away from the car for a period of time (like over night). Reconnect the battery in reverse order. My mechanic suggested that airbag systems in the car have capacitors that bleed just enough amperage back into the electrical system to keep some components from resetting. Leaving the battery disconnected for several hours lets those capacitors discharge. He may be full of hooey, but it has worked for me on my older cars where keyless systems (door pads) were confused.

New car? My 08 Sonata has been faultless.

 

Thanks, Ken. I may try that and I will definately remember it. I am going to take the car to the dealership tomorrow and have them check the alternator. It sounds like that may be a big part of the problem. It has not been replaced on this car and with almost 160,000 miles, it may be due. I am considering another Hyundai. Mine has been a great car. Only odd little problems like the turn signal lever breaking. Overall, the best car I have had.

 

no don't reconnect the batt. in reverse order, what you do is try to touch the negative and positive terminals together then it should reset.

 

Sorry. To save words, my advice did become obscure. Madindian1 is correct, touching the leads together should help drain any capacitors in the system. My intent regarding the "reverse order" concerned reconnecting the battery to the system.

To clarify, when disconnecting a battery from the wiring harness, it's always best to disconnect the ground lead (negative) first and then the positive lead second. When connecting a battery to the car, it's best to connect the positive lead to the positive terminal first and connect the ground or negative lead last. Anyone who's done this in opposite fashion and had a wrench on the positive terminal come in contact with a metal part knows you can get a nasty burn from the spark that results (even if the hydrogen gas coming off the battery isn't ignited). Yes, always make sure the leads are connected to the correct corresponding terminal.