Voltage drop

[tbauer03]

I noticed the other day when I got into ty the volt meter was at the half way point on the stock gauge, normally it is about at the 3/4 mark. I verified on DM from a file I ran just a couple days earlier that I am indeed getting less volts. before I was around 13-14 now I am around 11-12 volts. My dash gauges would occasionally flicker as well. I am guessing my alternator is one the way out since this drop occured so rapidly but I also read about some people not getting enough volts to their ecm and modifying some wire to increase the volts it sees. I did remove the ecm to change out the heater core before I noticed the volt drop. The battery is also new.
I briefly looked at replacement alternators on advanced's website and they all say they are 105 amps and 12 volts output, so i am also wondering if the 11-12 volts I am now seeing is more aligned to what I should be seeing and my previous 13-14 is higher than it should be.
Thanks

 

[69gtojeff]

Re: Voltage drop

Your battery voltage should be about 12.6 when charged (engine not running) and about 13.7 when charging. This number depends on the voltage regulator in the alternator. You are running on battery only.

 

[BoostedSUV]

Re: Voltage drop

Before I did the ECM voltage mod I was seeing 13.7 at the ECM (using DM) at idle/cruising. Under WOT the volts would show 12.1 at the ECM. After the voltage mod I got a steady 13.7 even under WOT. If the volts you are seeing are at normal driving or idle speeds I would say your ALT needs replacing. Did you test the voltage at the battery like Jeff mentioned or are you just using datamaster? Datamaster just records voltage at the ECM