2003 Chevy Silverado electrical nightmare?

[merganser]

So my wife went to start the truck this morning and it was completely dead... no unlock, no lights, no life. Checked the battery with a volt meter and it read .04... dead. When I hook the battery charger to it, the security/driving lights come on and kind of flicker and there is a nasty buzzing noise coming from up under the dash board on the drivers side. It is louder on the inside of the cab than in the engine compartment. There is what looks like possibly a computer module (just a guess) mounted on the engine side of the fire wall. The noise seems to be in that general area but on the inside of the truck. I can't really see anything but maybe a vent housing on the inside area, up behind the linkage for the emergency brake. I unplugged the battery cables and then took a reading on the battery... It read 9v and was climbing. So 0v when battery attached, 9v and climbing with battery disconnected.I hooked the battery cables back up and left the charger in the on position. Played around with the fan and the ignition and different things an nothing made a difference. I turned the hazard flashers on and off and it stopped buzzing and the normal door open key in the ignition dinger started to ring. Once I removed the voltage supply, and then turned it back on, the buzzing sound started again. I couldn't get the ringer to operate again. Unfortunately I was not there when she turned the truck off so I don't know if it was buzzing then or not. I can't believe she wouldn't have heard it if it was buzzing... who knows. One other symptom is that she said there were a couple of times when she went to drive the truck and all of the radio stations presets were messed up. She thought someone was messing around with her. SO, any one have any idea what I am up against. I called one Chevy dealer and the service man I talked to hadn't experienced anything like that before. I did unplug the seat fuse and the door fuse and the plugs in that little box under the dash, but nothing changed. I haven't played with the fuses in the main fuse box yet.. I will do that after work.

[Macgyver55]

It sounds like simply a bad battery to me. There are many relays, chimes and solenoids that will make all sorts of noises when voltage is low. Try installing a KNOWN good battery or at least try jump starting it and see what happens, then report back!

[Shack]

Yep, try what M55 just said first and then report back.

[Scott K]

Ya what they said

[merganser]

Wouldn't my 50amp starting charger provide enough juice to overcome a bad battery. Plus, how come as soon as I add juice, I get the buzzing and none of my guages work and when I unhook the cables from the battery I get voltage on the battery. I think something is shorting out... I will try the battery.... I think the battery is relatively new though. Maybe kiss is the answer, but it sure seems like there is another problem.

[Shack]

Somone can explain this better, but if you have a dead/bad cell battery, it seems even a 100 amp boost does nothing.

Quote:

and when I unhook the cables from the battery I get voltage on the battery.

How do you know you are getting voltage? If it is a spark, it is from the charger's power, not the battery.

Bad batteries do some strange things to your elec. system.

[Jeremy airjer W]

I have had several that would not jump especially GM side terminal batteries. I have also had to put the jumper cables directly to the starter on a few just to get them started and into the shop.

A new battery is a good start, I would bet that it has been getting weak and the radio presets where resetting as the vehicle was cranking over to start. If its the original battery than it is already 5 years old, I don't think it would be that bad of an idea to replace it anyway.

[merganser]

KISS!!!!! You guys were correct! That is why I push a pencil and you guys fix the autos. So here is what happened. My wife has a little wicker basket she uses for a waste basket in the truck. It got pushed over just enough to activate the manual switch on my brake controller and apparently the brake lights were on all night long. Everyone was asking if something got left on in the truck and I kept saying it has the battery run down protection... nothing should have been on. Well, I didn't even think of the brake controller. I have never heard such a weird buzzing noise before..... not sure why it acted the way it did. You guys were right about strange things happening when low voltage occurs.

[merganser]

Thanks for your help! This site is awesome. Shack, in response to your question, I tested the battery with a digital volt meter with no battery cables connected. It had about 10 volts. That is why I thought I had a short.... it ran fine the night before and when I checked the battery with the cables attached, it had zero voltage. I guess that is because the brake lights were on. Oh well, all is good for now thanks to you folks. Have a great memorial day weekend.

[jwhjr]

Great to hear you got the issue figured out and it was a simple "fix". Great info guys!