So I have a 03' Chevy Trailblazer LT and for the last 3-4 months the car would die if the lights were left on for a short while, (And I dont' mean the head lights all night)

Like if we left the interior lights on for about a half'n hour then it would be dead.

So I figured it was the battery, well I just replaced the battery 2 days ago, and right away pulling out of the auto store where I replaced the battery, the car died, and I was like...?
So I checked the terminal connections and tightened them, and it started right up again.. And I've been driving it since, and it seems to run fine, EXCEPT when I stop, at a stop light, in the driveway, pulling up to a "T" intersection.. it acts like it wants to die, idling around 1k rpms and then dropping down to 300rpms...then back up again to 1k... then back down to 300...


So what do you guys think it is? bad battery from the parts store (napa) bad alternator?

thanks!

Sounds like the alternator.

I'm sure if you went over to the guys on GMTNation.com or Trailvoy.com they could give you a definitive answer or at least help you rule some stuff out. I prefer GMT, great crowd and fast responses.

I'm still saying alternator for the charging problem and the idle issue sounds like a vaccum leak or a bad iac valve.

You disconnect the battery on a electronic throttle bodied 4.2 & it will lose the "learned" throttle angle.
Clean the throttle bore out really well.
get it started after putting all the cleaner into it, & clear it out. Shut it down & disconnect the battery.
Reconnect & relearn the throttle. Start it up nothing on (no load) let it idle in park for 1-2 minutes.
Same key cycle, run it in drive for 1-2 minutes. Run the A/C in drive for 1-2 minutes.
After that turn the steering wheel to each lock a few times.
Then drive A/C on & off, & it should have relearned the throttle angle.