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I have a 2008 Pontiac G5. The battery is about 7 months old and I had it tested and it is perfectly fine. Connections to the battery seem solid and clean. However, intermittently when I try to start the car, it's completely dead. No noise when turning the key, no interior lights light up, and I can't remove the key. Behavior of a completely dead battery. If I leave the key in, open the door, and close the door again, within a few minutes, the radio will light up. I can then start the car and all is fine until the next time this happens.

Other items of note when this occurs are that I've noticed that when the radio does come back on, the time is reset and it's switched back to AUX; like I just reinstalled a battery. I don't know if this happens each time. This is my daughter's car and I just noticed this. Also, upon the first start after this happens, sometimes the gauges won't go "true" immediately. I noticed the gas gauge wiggled at empty for a good 30 seconds until it finally shot up to the proper level. This does not occur every time. And sometimes once it does start, I've noticed a clicking (like something switching) under the hood in front of the steering wheel or sometimes it seems like the CD changer is trying to do something. Again, this does not happen each time.

All of those things in the last paragraph ONLY happen after I start it after it's been dead. And each thing is also occasionally. Most days, it starts just fine and there is nothing wrong with how anything operates. I'm a little stuck on what this could be and I cannot get any of this to happen reliably. It's completely random behavior.

  • You have a loose electrical connection someplace, take it to an automotive electrician to hunt it down, it's unlikely you'll be able to do it yourself. – Robert S. Barnes Jan 23 '18 at 10:34
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The first thing I would do is verify solid connections for the battery B+ cable and the ground at BOTH ends of each cable.

That verified, I would do a voltage drop test on both cables. Instructions for this are readily available, and if you have a voltmeter it's quite simple.

While it's a relatively new battery, there also exists the possibility that an internal lead plate jumper has a crack. The next time this happens (car appears "dead"), measure the battery voltage before you slam any doors. A low or zero voltage indication suggests a bad battery with physical internal problems.

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  • Good suggestions, I will try all of these. This particular car has the battery in the trunk and the fusebox under the hood so it makes things a little more difficult for me to test between the two. – heath Jan 23 '18 at 18:29

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