Resetting a 2003 Chevy Avalanche after changing out batteries

[Steve Keaton]

I just changed a dead battery out of our 2003 Avalanche.  Now it runs sluggish and stalls unless I have my foot on the accelerator.  I have read and seen far too many backyard mechanics try to show how easy it is.  Please help.  Is it just detach the negative cable for a few mins or should I pull fuses instead.  I need help please

[KARNUT]

7 minutes ago, Steve Keaton said:

I just changed a dead battery out of our 2003 Avalanche.  Now it runs sluggish and stalls unless I have my foot on the accelerator.  I have read and seen far too many backyard mechanics try to show how easy it is.  Please help.  Is it just detach the negative cable for a few mins or should I pull fuses instead.  I need help please

Unless there’s a big difference between an 02 to an 03 there’s something else going on. I recently changed my battery it was undo terminals install new battery. Hook up the terminals. It was that simple. 

[Jsdirt]

Make sure your cable connections are tight, and that there is no hidden damage to the cables hiding under the jacketing.

 

I had an ATV to diagnose many years ago that had similar symptoms, but all my tests checked out good. I was starting to pull my hair out in frustration when I disconnected the battery and found the negative cable was hanging on by only ONE strand of copper! Was tough to see, since it was right up on the negative terminal. That one strand would get hot, and resistance goes through the roof. No wonder the electric start didn't work. I'd get a click, and that was it. We pull-started it and it would run, but very poorly.

 

If your cables are all tight and not damaged, then just disconnect the battery for a half hour. After a couple minutes of the battery being disconnected, touch the positive and negative cables together for a few seconds, then walk away for a half hour, reconnect them to the battery, and try again. Sometimes this is needed to get the "stupid" out of the magic box. When connecting the negative cable LAST, be sure to firmly install it, and quickly, so that it doesn't "double-tap" - sometimes that can induce some strange behavior in the computer. Make sure key is OFF, and all accessories are off, door closed, etc., so that there isn't a big spark when you reconnect.

 

Welcome to the world of computer-controlled automobiles!