Ok, here is my question. what should the voltage be from the battery connection at the fuse panel to the alternator, when off and when starting? I have a 2011 LT that has had alternator, battery, starter, negative cables and ecm replaced.

 

Engine off=12.75; engine on variable 12-17.
Why has all that stuff been replaced?

 

Because I am an idiot that likes throwing good money towards bad results. I am trying an expensive process of elimination on this project. I measured the voltage from the post on the alternator to the forward post on the fuse box. With no power it measured less than one volt. I had my better half start the car, the voltage went to about 9. I am thinking that the cable might be corroded and providing way too much resistance.

 

How can you measure voltage between 2 ends of a wire? Either you are phrasing different or you don't know how to use a VOM.

You should be grounding the black lead and probe the fuse box lug, the starter lug, the alternator lug with the red lead.

Of course just stating what the problem is would help. Does this really belong in the Audio Visual forum?

 

I'm sorry. I had the black lead grounded and was reading at the fuse panel which had good voltage of over 13 and at the alternator was about .5 volts. With power the fuse panel was still above 13 and at the alternator was 9. My issue is the car seems to have a problem keeping good voltage. I replaced the alternator because the brushes had totally run down and not touching the commutator on the alternator. I replaced the starter due to a broken post on the solenoid. The ecm was on the recommendation of a mechanic that I work with. That probably was not the smartest move on my part. The service ESC and service traction light would come on and it would lose lights and radio, then everything would come back and the car would run fine for a few more minutes before it died. I put a fresh battery in it to get it home, checked the voltage and it had already lost 2 volts.

 

Also, thank you for your help.

 

Best thing to do is retrace and check your work,

A: are all connections correct and clean and tight?

B: are all ground connections clean and tight?

C: are all the under hood fuse box relays and fuses pushed all the way into their places and clean and tight?

sometimes the fuse box halves work loose, have you inspected the fuse box?

D: now have you inspected the in car under the console fuses and relays , again clean ? Tightly seated?

a little dielectric grease helps, these trucklets like their voltage just right! All connections clean and tight!

Also , load test that battery, even a brand new battery can have a dead cell or is not fully charged, a new alternator might not fully charge the system, and a slipping serpentine belt with a weak tensioner can cause havoc.
the nice part is checking these things don’t cost you anything but time!

 

Only thing I haven't done is the load test. The fuse box is snug to the bottom half and all fuses/relays are seated, both under hood and inside car. every cable that i removed was scuffed with emery cloth as well as where they connect. I have actually replaced the battery and it had good output. I truly appreciate any and all help. This has been a true P.I.T.A.

 

I know, but we have to be sure so, a load test is in order.

 

I will do one. Thanks.