03 Silverado alternator/battery question

[Snopro440]

I have a 2003 Silverado 5.3 and I noticed about 2 weeks ago that the lights (dash, headlights, plate lights) were "pulsing" quickly. I noticed that the voltmeter was pretty consistantly going back and forth from about 13.9 volts up to about 14.5-15 . I took it to a couple auto parts stores and they tested the alternator on the truck and both said it tested good. The second happened to touch the positive of his multimeter to the case of the battery near the caps, and it read 3.2 volts (one lead on negative the other on the case of the battery). I went to a batteries plus and they said that the battery is no good, and that it is putting out less than 500 CCA and needs replacement.

Would a defective battery (its about a year old) cause the pulsing of the lights and the issue with the voltmeter? I had simply assumed that it was a voltage regulator problem, but I guess I really don't know. Does anyone have any advice for me? Thanks!

[j cAT]

Originally Posted by Snopro440

I have a 2003 Silverado 5.3 and I noticed about 2 weeks ago that the lights (dash, headlights, plate lights) were "pulsing" quickly. I noticed that the voltmeter was pretty consistantly going back and forth from about 13.9 volts up to about 14.5-15 . I took it to a couple auto parts stores and they tested the alternator on the truck and both said it tested good. The second happened to touch the positive of his multimeter to the case of the battery near the caps, and it read 3.2 volts (one lead on negative the other on the case of the battery). I went to a batteries plus and they said that the battery is no good, and that it is putting out less than 500 CCA and needs replacement.

Would a defective battery (its about a year old) cause the pulsing of the lights and the issue with the voltmeter? I had simply assumed that it was a voltage regulator problem, but I guess I really don't know. Does anyone have any advice for me? Thanks!

first the battery must be load tested...if when testing the battery does not properly have a solid amount of current of the proper amount the battery is defective ...this is the only good quick test available....

so with a new good battery and the / ALL terminals /connections clean and not corroded you should not have any issues ...

with what you have now it could very well be an internal cell open/ shorting intermittently....

I never have them install a new battery...I will bring the battery home set on charger for a few hours till it is good [auto charger ] then install in the vehicle ...this will prevent battery/alternator damage....

with the battery out of the vehicle wash with baking soda and water the battery mounting area and repair any rusting ....

[Snopro440]

I tried a brand new battery, and the issue is the same. I have located a GM service bulletin that would seem to apply. It is number PIT3170E . I'll have it looked into.

[enjun]

had the same problem 2 weeks ago on my 2000 5.3, alternator read good at the autoparts stores, but it is your alternator, one thing if you do put a reman. or new alternator disconnect both terminals to the battery then hook (+) up first. For some reason if you don't disconnect the battery it will blow the diodes in the alternator.

[wdchparks]

Twice now one with my Silverado and one with my Avalon I had Autozone test my altenator and battery. In both cases they said the battery was good and the altenator was good. I had no start problems. They were wrong someone here mentions a battery load test which they dont do. In past cases what you are describing sounds exactly like a regulator/altenator problem. I am sure you have already made sure your side terminals are very clean and firm contact. Side terminals allow for very little contact so they have to be tight and clean. Good Luck

[j cAT]

Originally Posted by Snopro440

I tried a brand new battery, and the issue is the same. I have located a GM service bulletin that would seem to apply. It is number PIT3170E . I'll have it looked into.

you must check all those battery connections ...there are more than the connections at the battery terminals ...follow the wires ..