Battery Light and exterior lights blinking

My daughter had an issue with her 2003 Impala where the battery light was flashing on. A few days later the exterior and interior lights were blinking on and off while it was parked in the driveway. We replaced the alternator and had to get a new battery. That was 3 weeks ago. Soon after doing this my daughter said the battery light came on twice but then stopped. Well yesterday it started doing it again with the battery light on and the lights flashing on and off. Any ideas? I read something when I googled that said an ignition switch possibly?

Her boyfriend is worried it could need a new computer?

I also ready somewhere that it could possibly maybe need a computer flash?

When everything starts flashing, put a voltmeter across the battery and tell us what you get for a reading.....

Thanks! I will have my daughter do that. Any idea what this could be while I wait for her to do this? It was good for some days but started up again today.

Still unable to get a volt reading as we do not own one and everytime it does it she takes it to the shop here in town and it stops doing it. A friend of mine said it sounds like a bad ground wire. We checked and cleaned the ones going to the battery and it still does the same. Every night we have to undo the negative on the battery so it doesnt start flashing in the middle of the night. I plan on putting it in the shop soon but fear what they may charge to diagnose it. I have 2 friends who are mechanics who looked at it and are stumped. I also failed to mention when the car lights are going on and off and the clicking noise in the dash, the battery needle surges up and down on the dash.

Anyone? Any ideas?

Is the click from the drivers or passengers side??

Drivers side I would look at the ignition switch and wires. Pass side I would look at the automatic lights sensor.

Any aftermarket alarm or remote start?

I will have to check which side the click is coming from. I called my daughter to find out. It is the factory alarm and no remote start. There was some minor flooding about a year ago in the car. It was only on the floorboards. Insurance replaced the entire interior. I am wondering if this has something to do with it?

My daughters bf is also bringing up a possible BCM? Hoping its not that!

I will get what side it is clicking from and have him check those items.
Would either of those cause the lights to blink?

If it has keyless remote and the lights flash when depressed, I would suspect the keyless system.

It is coming from the drivers side. They said it sounds like the battery relay clicking. Also today was a bit cooler and the car has not acted up at all. It seems to only act up on warm/hot days?

Ok so it seems the car is only acting up when it is hot outside. If you cool down the inside of the car with air conditioning the problem stops..as soon as it sits in the hot sun and warms up inside it acts up again? Weird?

Anyone trying re-programming the BCM? ( body Control Module)

Sounds like a glitch in the BCM, this pesky module controls everything from security to lighting.

To re-program the module.

1. Turn the key on and off.
2. Remove the key. Places passlock system in operation.
3. Replace the key, make sure all controls are off, radio and lights are OFF.
4. Turn the key to on position (all dash lights are lit) and leave on for 30 minutes. Do not try and start the car.
5. After 30 mins, turn off the ignition and remove the key.
6. Replace the key and start the car.

See if this fixes your issue. Remember the module controls it all.

John