Ok. I am on the fourth alternator and I the single wire is fielding. The battery light comes on when you turn on the key. The new alt has been back off 4 times to Orielies and Auto zone consistently test good every time.. One more symptom. When the battery was dead I jumped it. When the jumper cables were battery to battery it started and ran off the other battery. When I ran the negative to theframe or engine it would not start

 

it might help if we knew what you were working on

 

& post the fault code that has set.

 

Post the voltage across the battery terminals with engine running like 2000 rpm.

 

Most of these alternator questions seem to be centered around that single wire alternator. It's the same question I have read a million times and the same in effective answer is given every time. Question: I have change d out everything I could On the charging system and it still won't charge,. What do I need to do? The ineffective answer from the forum mechanic: first all do you have these fifteen readings written down from your multi Meter test s.
Regular guy who probably is to poor to pay someone to fix the problem. Also needs the trick on Monday or no work, says huh what's a multi Meter....

 

Based on the first post, and nothing further, I'd replace the ground cable making sure the grounding point was clean, and tight.

 

so...... you dont know what your working on and you dont know of any fault codes and you have no multi meter????????

 

Could be the wiring to the alternator.

 

If no multimeter:

 

its hard to offer anything specific without knowing the build. tahoe and sub were made for a lot of years. there are ecm controlled systems and voltage regulator controlled systems.
the shotgun approach didn't work for you and probably cost more than having it fixed at a shop. If you want to diagnose this so you only replace the bad part...you need to perform tests and take readings. this requires equipment. google multimeter or dvom. depending on the model year...fault codes read from a scan tool are helpful as they give you a starting point on where the fault lies.