Problem with 2002 Silverado

[Crunchy]

My 04 Silverado had the same issues.  I had the alternator bench tested and it checked out ok.  I eventually drove the truck to Autozone and had them test the alternator while it is running.  Alternator was bad even though it bench tested fine. 

[Slimdog350]

I would have your battery load tested to make sure it's good. A lot of times when your alternator goes out you won't know it right away because your truck is running off the battery so it seems fine. Also test the amperage from the alternator. It could put out 14v all day long but if there is no amperage it won't do any good. There is a set voltage that the ECM and body control modules operate on. If your voltage dips below that setting you start to have issues. Hope you figure it out. I don't think it's anything to crazy. Keep us posted!

[lostbackpacker]

You need to check each individual cell on the battery. Load testing won't show a bad cell. To check the alt   Wth truck running take pos  battery cable  off. Load alt by turning on all electronics. If it dies, alt is bad.

I think each cell should read 2 amps

[bobcat]

If I take the battery to NAPA or another auto parts store, will they be able to do the proper testing?

[jackelope]

If I take the battery to NAPA or another auto parts store, will they be able to do the proper testing?

Yes.

[jackelope]

. To check the alt   Wth truck running take pos  battery cable  off. Load alt by turning on all electronics. If it dies, alt is bad.

??

[bobcat]

If I take the battery to NAPA or another auto parts store, will they be able to do the proper testing?

Yes.

Thanks. I will try that first. I've got a NAPA just down the road.

[washelkhunter]

6 yr old battery would and should be the first thing to replace.

[jackelope]

Really, things should be tested and diagnosed properly before people start throwing random batteries, alternators, fuel pressure regulators, and whatever else the next guy comes up with at it.

[snowpack]

Really, things should be tested and diagnosed properly before people start throwing random batteries, alternators, fuel pressure regulators, and whatever else the next guy comes up with at it.

Fuel pressure regulators, ground wires and the fuel pump relay can be checked with no cost or real time investment.  Easy enough to do with hardly any tools and helps eliminate possibilities that can be masked by electrical gremlins.

[HntnFsh]

Really, things should be tested and diagnosed properly before people start throwing random batteries, alternators, fuel pressure regulators, and whatever else the next guy comes up with at it.

Good advice.

[Woodchuck]

I agree with Jackelope but will say this. At 6 years old the battery is at the end of it's life expectancy, replace it as a preventative measure. Then go drive the truck for at least 15 minutes to relearn idle strategy. At a minimum it will eliminate a step in testing if you take it to a shop. Batteries can get bad enough that the alternator can't keep up. 

[coachcw]

I have had chevs run very poor after disconnecting the battery or even changing the air filter , the fuel adaptives may take a few minutes to recal. this can be caused by lack of fuel preasure and dirty injectors . I see quite a few problems with the intake gaskets on those models sucking air this can cause a lean condition but often they have enough fuel trim to smooth out after they run for a bit. the electrical problem that your having really seems like a alternator to me I'd throw a volt meter on it and read the battery post on the back of the alternator and compare it to the post at the battery should have less than 4 tenths of a volt drop. most gms will run 14.1 to14.2 running . turn all acsessoires on and if it dosnt maintain atleast 13.8 i'd lean toward the alternator , you may have to let it run intill the alt gets hot say 15-20 minutes .

[Slimdog350]

You need to check each individual cell on the battery. Load testing won't show a bad cell. To check the alt   Wth truck running take pos  battery cable  off. Load alt by turning on all electronics. If it dies, alt is bad.

I think each cell should read 2 amps

It makes no sense to test each individual cell. If you load test a battery and it has a bad cell in it it will fail. The load tester will show your surface voltage. When you load the battery to half your cold cranking amps if it's bad the voltage will fall and so will the amps. Each cell should have 2 volts in it not amps. I agree with jackelope. Test first and replace after. It can get expensive throwing parts at something. Check your connections, cables, battery, alternator, etc.

[jackelope]

I've never even heard of testing each individual cell. With that said, I'm fortunate to have a sweet battery tester sitting in a cabinet right around the corner. When a battery has a bad cell, it tells me.