new alternator and not charging. what could be the problem
Could be the battery, corroded, or loose battery cables, or bad voltage regulator. Take the truck to your local auto parts and they can check it free of charge
all above are correct...diode...who and when was the alt replaced?? as ts said some time ago >It looks like your trucks charging system is computer controlled, have the engine control system checked, the fault might be in the ECM. its called a VAT TEST
Looking for a Used Sonoma in your area?
CarGurus has 570 nationwide Sonoma listings starting at $1,799.
Search GMC Sonoma Questions
GMC Sonoma Experts