Sudden Electrical Failure

I have a 2004 Chevy Avalanche. A couple of weeks ago, I drove into my driveway and turned the ignition switch to off. Immediately, there was no electrical activity at all: no lights, no radio, turning the key to start produced nothing. Because I park outdoors and it was very dark, I decided to wait until morning to diagnose the problem.

The next morning, I opened the vehicle door to pull the hood latch, and I saw the

dome light on! Hmmm, I had electricity. Using my digital voltmeter, I measured

the battery voltage at the battery terminals and got 12.56 volts - fully

charged. I turned the key, and the car started and ran perfectly.

For the last 2 weeks, the electrical is still working.

What could have happened?

Is there some inline circuit breaker which overheated, cutting all electricity

until it cooled down?

You have got to love intermittent problems. You just never know when they are going to show up.

The problem is most likely in the main power buss circuit. I suggest you remove and clean the battery connections using a battery post cleaning brush just to eliminate that point. Also check the main power going to the fuse panel under the hood for any bad connections. You may want to try tapping on suspected areas of trouble using a screwdriver handle and watching for a power failure. The ignition switch is another suspect area also.

One other thought is the battery itself may have a bad internal connection. Most likely not, but it is a possibility.

You the lights would not turn on? Do you know if the brake lights would illuminate? Does sound like main power circuit, but if it happens again try to find out if anything is getting power.