hey guys
so i have an 03 sivlerado 5.3 and i need help. whats going on is when i start the truck up voltage is normal alittle over 14v then i can turn on everything (lights,foglights,heated seats,wipers,stereo with gain for sub fairly high and the heater on with blower on max) the volts doesnt really drop maybe to 13.7 ish with all his on but when i turn on the rear defroster it dims all the lights and voltage drops to 12-12.5v when this happens it bogs the motor not bad enough to die but you can tell it takes a toll on it i just put a new alt on t today and still the problem is there the alt i took of was less than 6 months old when i had it tested vol reg failed at 18.1v the other thing is when the voltage is low and i rev up the motor the voltage goes back up to 14v unill i let off sory the post it so long thanks any insite would be helpful thanks

 

Anyone got any ideas?

 

Sounds more like a low idle/Dirty throttle problem than a alternator problem.

 

I will have to try that thanks man. I never thought to go that direction but it makes sence.