2003 Chevy Avalanche 1500 (5.3 V8)

Last week the when starting it up and letting it idle or at idle speed when coming to a stoplight, the thing would just completely die on me. I noticed on the voltage gauge (which normally reads 14 volts) it would start to drop down to around 11 volts just before it was about to die. It will also start to drop to that if I didn't give it a little more gas than idle speed whenver I was stopped, or starting to come to a stop. Otherwise...you guessed it...it would die!

I took the truck by Checker and they hooked it up to their handheld computer and had me rev the engine. Then proceed to tell me the alternator is charging. Duh, seems counter productive because my problem of it losing voltage is not when I'm revving it! It's when it's at idle speed or coming down to idle speed.

My thoughts were it's the alternator. Any other ideas?

Seems a few years ago it started to do this same thing for my wife when I was out of state for an extended period of time. It eventually cleared up and started running normal for her. But this time it's back and not clearing it'self up.

 

Are you getting a check engine light? Would not be alt. you would not be able to crank it back... battery would be dead. Clean mass air flow sensor will make one die at a stop.

 

No, no engine check light.
Interestingly enough, after the truck was sitting for a week I came yesterday morning to start it up and it was completely dead! Jumped it and go it running but then same old thing, wanted to die if I let off gas or driving and came to a slow down or a stop.

It is idling at 600 rpm. Is that too low? What is the mfg recommended idle speed?

I cleaned maf sensor about 12000 mile ago. Is it time already for a new clean?

 

Did they test the battery as well?

 

Yes they did. The battery is 2 years old.
I also just did an alternator test with my battery charger. At idle is tested GOOD. With Load (as many electrical items turned on as possible) it failed. Hmmm.

 

All I can say is that if your battery was completely dead,then the problem is with the battery or the alternator,or maybe both. Take your battery terminals off and clean them with a wire brush to make sure that your getting a good connection. Something small like that could be the entire problem.

 

Yeah terminals are clean. It doesn't have post type terminals on the battery. Instead they are a bolt that screws into a built in nut/divot thing on the side of each battery. They are very clean.

So I did replace the alternator. We'll see if that does anything for it.

 

Are you running a system on the same battery?

 

No not running any extra systems, just stock stereo and nothing else. This truck has been plagued by electrical gremlins since I purchased 3 years ago. All parts fixed and replaced at my own expense.

1. Gauge cluster
2. Ignition switch (causing vehicle to stall and not shift properly)
3. Head unit/cd player.
4. Alternator.
5. Steering wheel switches for radio controls.

What's next...the engine or ECU!?

 

replace the alternator