Chevy truck battery drain

Maintenance/Repairs
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1

I have a 1999 chevy k3500 with a 7.3 engine. When I park the truck for a few days the battery goes dead even though the ignition switch is off. I have to disconnect the battery to prevent this. The radio light stays on after the ignition key is turned off. When I turn off my ignition key on my 1998 chevy the radio light is off. Any ideas to prevent this would be greatly appreciated.

2

Check that the door switch is operating properly.

3

Aftermarket radio? Could have been wired from something that stays hot all the time. Wire it fron the acc. terminal of the ignition switch.

4

The easiest way to find out where the drain is use an amp meter on the battery terminals and remove the interior related fuses till you see the drain go away. (some auto stores will let you use theirs)

Start with the radio of course. That would be on the ACCessory circuit. (assuming you’re referring to the illumination lights as a clock being lit may be normal, the illumination lights would be enough to drain a battery after a few days) Being on the accessory circuit it may be the ignition switch itself. If there is a solenoid in the accessory circuit where you put the ignition switch in the ACC position and you here a click, that could be going bad. Its easy enough to switch from ACC position to off a few times to see a spike on the amp meter, too. You could remove the ignition switch and turn it upside down and apray some wd inside and test it, too.

If the radio isn’t the culprit then I’d bet the courtesy lights or anything on that circuit with or without timers would be likely.

Also check the doors by opening and closing slowly while testing especially the drivers door first as it’s most used. It may be a worn wiring harness inside the door if the courtesy light circuit fuse shows up as the sure drain and keep an eye on the radio lights while doing this test, too. A negative ground (short) could also keep the radio lights illuminated.

pain in the butt huh!!!

5 
Is there an antitheft system?  They, by nature stay hot.  They also can use a fair amount of power.  After market systems seem to have a lot of problems with this, even OEM systems have been known to cause problems.
6

Thanks. This looks like a good plan. I will give it a try.

7

Swap radios with you 98 into your 99 and see how things go. Removing a radio in a 99(or 98) full size Chevy pickup takes all of 30 seconde. Do you know how?