Fluctuating Voltage

[04SS6.0]

I have a 2004 Silverado SS

I have been getting irregular voltage readings. The voltage meter will go back and forth between 14 volts to half way mark between 14V & 9V. When this happens lights will dim, if the heater fan is on it will slow down. Even when it was cold -20C it would almost want to die & actually died a couple times when first starting the truck (it would start no problem, but after a few seconds it would go back and forth on the volt meter & when it would dip lower thats when it died, that only happened about 4 times, & hasnt done it in a few weeks, but it hasnt been that cold again yet..) . This problem happens when idling, braking & coasting. It does not happen when my foot is on the accelerator. It happens randomly & happens pretty often i notice, especially when you first start the truck. It doesn't seem to matter what you have turned on or off for electrical loads. 

I have a new battery, I thought it was the alternator so i just replaced it & upgraded it at the same time from the 105A to the 145A. That made no difference it still does it & since its a 2004 it doesn't have that "voltage regulator" that they have in the 2005's+. 

What else could it be? corroded wires / bad connection from battery, alternator & starter? The starter itself? (Has 0 issues starting at all)

[diyer2]

Check all the ground wires to the frame, body. 

 

;) 

[riverbanks]

I would also check power supply wires,a easy test is to wiggle wires to get it to misbehave or stall

[ahill16]

Were you ever able to figure out what the issue is? I'm having a similar experience with my '02 Silverado 1500. Battery's only a year old. Autozone told me one of the cells in the battery had gone bad, but I don't know that I trust that diagnosis. My mechanic suggested the alternator was the most likely cause, so I replaced it, but the problem hasn't gone away. 

 

It fluctuates when I idle, when I decelerate, and when I'm accelerating up until I hit about 30 mph or so. It also jumps pretty wildly when I shift from park to drive and back. I would appreciate any and all insight, before I go back to my mechanic