2003 Silverado K2500HD won't crank

I have a 2003 Silverado K2500HD 6.0 gas with approx 48,000 miles that has a couple issues; I"m not sure if they are related or not though. I use this truck primarily to pull my gooseneck to haul tractors around and have not averaged 3k miles a year over the last 5 years of ownership (it sits a lot).

1. Over the past winter, it would run the battery dead if not driven at least once a week. I noticed that the battery light in the instrument panel was faintly illuminated all the time even when the truck was shut off. This was hard to see unless it was dark outside so I thought I had something with a small draw on the system. The only add-on to the truck is a Tekonsha break controller that is wired using the factory harness. Even when unplugged, the battery light would still be faintly on. I went to the local auto parts store that put their test equipment on it and told me that everything checks out on the charging system and that the 2 year old battery is still in good shape.

2. This spring, all power went dead in the driver"s door. The power locks and power window as well as the key fob would function on the passenger side but not operate the driver’s door. This went away and came back several times. Eventually, it started functioning normally again and has been fine for 3 months or so.

3. Today, I went to start the truck and the drivers door would not unlock using the remote fob. I unlocked using the key and when I got in, I noticed that the security lock indicator on the dash was illuminated solid -not flashing like the owners manual indicates it should. As soon as I turn the key to the start position, all of the dash goes black and it will not crank. I thought the battery must have been dead again even though my father used the truck Monday so put the charger on it and it was taking a good charge. After charging @ 20-30 amps for 15 minutes it still has the same symptom. Also, while looking for blown fuses, I noticed that the #5 (ign 1) relay under the hood started cycling as fast as it could all on its own with the key in my pocket. I pulled the relay and put it back in and it did not start cycling again. I decided to go on to something else and disconnected the battery from the truck and put the charger on the battery. When I came back to the truck about 45 minutes later, I hooked up the battery and tried to start the truck; the security lock was not illuminated initially though the dash went black when the key was in the crank position and the starter did not engage. After that, the security lock came back on solid. Frustrated, I left it a few more minutes. It was getting dark outside and when I walked back up to the truck, I could see that all the dash “backlight” was on between half and full brightness. I could not get the dash lights to turn off. The dimmer switch is about half way to full brightness and is not turning on the interior lights. I gave up and disconnected the battery so it would not run down tonight. Note from item 2, I now do not see the battery light faintly when the key is off.

I’m confused and primarily concerned with issue #3; anyone seen this before?

Try turning the key back towards you as if you were turning the radio on. If the security lock is activated it should deactivate after 15 minutes or so in that key position. I've heard that works for some and not on others.

#1 Parascitic draw= something is pulling a small amount of power when the vehicle is shut off (ie light under the hood or glove box being on). You have to check the amp discharge from the battery when it is not running and pull fuses to find out what circuit the amp draw is on. Follow that circuit and check all items on it.

#2 Loose or Bad ground in drivers door- see if you can find the ground wire.

#3 Security system needs to be deactivated. Call GM and see what they say.

Good luck

Turn the key on to the ign. position (just before crank) and leave it there 15 to 20 mins. The security light should go away.
Sometimes this happens because the ignition tumbler gets worn out. Not likely as you don't have many miles on this truck. Although it could be that it has been started and stopped many times. The security system is based on a key inserted in the ignition to send a resistance value to the computer to determine if someone is starting the vehicle with a key or if someone has broken the ignition switch and is trying to hot wire it.
It also sounds like a separate issue with the drivers side door. Many times corroded connectors are to blame for issues like this. I would definitely suspect a corroded connector being as how it is so intermittent. If it sits for long periods of time moisture could collect and not get a chance to dry if there is no air circulating like there would be if it were driven every day.

One thought comes to mind, was this vehicle ever under water.......even partially? Did you buy it new?

Thanks for the replies. The local GM dealer gave the same advice about leaving the key on for 15-20 minutes. The security indicator never went out... It has now been towed to the dealer for them to diagnose on Monday.

To my knowledge, I am the second owner of the truck and do not believe that it was ever under water (although I can not prove that I did find record of the previous owner who actually lives ~5 miles as the crow flies from me and we have not had any flooding that would put a vehicle under water in the last 30 years that I have been alive). Before I bought it, I had the service records run from GM that did not indicate any major work had been done to the truck either.

When I get it back and clear out some space in my parents shop, I'll put my new amp clamp multimeter on the battery cable and start pulling fuses to try to find the draw. I use the truck more in the summer so the battery usually stays up without issue. I will open up the drivers door to try to chase any corrosion and/or ground issues also.

Got the truck back this past Tuesday evening. The dealer replaced the ignition key switch and the PCM to the tune of ~$1200. The truck starts and runs now...

During the repair though, the technician broke the plastic shroud surrounding the steering column so it does not snap together tightly now. I'm in negotiations regarding getting that fixed. Just wanted to let you guys know the result in case someone comes across this later with the same issue and can have an idea of what to expect. Thanks for all the help! -Brian