2008 Tucson: What's draining my battery?


This is a doozy. Follow along, if you can.

Over a period of several months, my 2008 Tucson began experiencing a series symptoms, which at the time, I didn’t realize were related:

• The stereo would occasional freeze up. It would still play, but the volume or channels couldn’t be adjusted without restarting the vehicle.
• The washer fluid motor stopped working. This was a continuous failure.
• The check airbag light came on and stayed on.

One morning, several months after the first symptom appeared, I went outside to find the hazard lights turning on and off randomly. The car would not start. I had the battery tested. It was drained, but not defective. After putting the charged battery in , the car still would no€™t start. I had it towed to the dealer.

Immediately after the car was taken off the tow truck, it started, the check engine light was off and the washer fluid motor was working. The diagnostic computer found no codes. The dealer cleaned and reattached the ground strap, and replaced the airbag pods as a precaution.

The car ran fine for several months, but then the radio and check airbag light problem started to appear again.

I took it to my regular mechanic this time. He could nâ€ot find anything wrong, but gave me a new battery to try as a troubleshooting measure.

After a few months, the problems are now starting again.


Are the battery terminals clean and tight? Is there any corrosion under the insulation of the cables? Is the alternator connections clean and tight? Are the chassis and motor ground straps clean and tight? Is the alternator putting out the correct voltage? I would also ohms check the alternator, they call it “generator”, fusible link. This would get the battery section and charging section, but not a parasitic drain. For that I would try pulling fuses starting with the horn fuses.


I wanted to post battery schematic too.