Battery is fine, but my car won't start - sometimes!

2005 Chevy Trailblazer LT.

Last night, approx 40 degrees and raining, we went out to my trailblazer and it wouldn’t start. The lights, inside and outside, all came on, but the car would not start. When we turned the key, there was dead silence and absolutely nothing happened. The engine didn’t try to turn over or ANYTHING. We decided we’d deal with it in the morning. When we went to start it this morning, approx 45 degrees and raining, it started right up like nothing ever happened. At that point we took it to get the battery tested, and the car pros at Walmart said the battery was just fine. So we took the car back home and decided it was a fluke. We went to start it this evening, it wouldn’t start again - the same situation where absolutely NOTHING happened, but the lights inside and outside would come on, though.

What do you think the problem is?

Thanks for all your help!

If this happens again, move the transmission lever to neutral and try to start your vehicle. If it starts, the problem may be in the switch that only allows the vehicle to start in Park or in Neutral.

If this doesn’t do the trick, turn the lights on and try to start the vehicle. If the lights dim considerably but nothing happens, the battery may be at the end of its useful life. Check the clock. If it has reset itself, this also indicates a battery that has low power output.

This truck has a few circuits in it that may be causing problems. One is the neutral safety switch. This prevents the starter from being used if the transmission is not in ‘Park’ or ‘Neutral’. Next time this happens, put the gear selecter on ‘N’ and try it again. If it starts, this is the most likely culprit.

The next is the starter relay. It is supposed to send current to the solenoid to activate the starter. This may be failing in cooler temperatures.

Corrosion on the battery and high amp leads is also a possibility. Corrosion could prevent the power from even getting to the starter. The battery cable must be checked on both ends for possible corrosion problems, at the battery and the starter.