Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by texas funeral man, Feb 13, 2013.
Battery runs down over night and headlights pulse bright then dim while truck is running
with all the connections cleaned and secure wires not corroded with the vehicle running check the voltage at the alternator output red wire. should be 14.5 volts engine on and cold. if its lower will all electrical on lights heater ac fan on high etc then the regulator in the alternator is corroded. this happen to me 3 yrs ago.
when you replace the alternator with new or scrap yard put charger on the battery before operating .
never purchase a re-built alternator ,as these are not good. I got the new alt with the updated alternator regulator module.
X2 on the alternator.
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