Looking for some ideas here. Has anyone ever seen charging voltage while the truck is running fluctuate from 14.20-15.30??? The voltage is all over the place never staying consistent for more than one second. This does not seem right to me but I am not sure where exactly to start and I would rather not just start changing parts on hopes and dreams.

Sitting with the key on but engine off I have 12.30 volts.
As soon as I start it voltage bottoms out at 10.18 volts.
Truck started and running voltage is between 14.20-15.30.

2007 1500 HEMI.

Thanks for any ideas.

 

How old is the battery?

 

Well i am not sure, the battery has no date and it was in the truck when i bought it last september. I will say that the truck turns over kind of slow IMO. It always starts though.

 

Try a battery first. I will cause the alternator to work harder. It could also be the voltage regulator going bad.

 

Is the voltage regulator a part of the alternator or is it part of the trucks computer?

 

Alternator as far as I know.

 

Do you know anything about the battery temp sensor? Should all trucks have them?

 

Yours should. Not sure if this could cause your issue.

 

I pulled the battery and replaced with a new one. While it was out i looked for the temp sensor but i do not have any sensor mounted in the battery tray. I do not see any electrical plugs hanging anywhere like there may have been a sensor at one time. I guess maybe i need to have my local dealor run my vin and tell me if i should have the sensor? Any other ideas?

 

Regulator is in the PCM


If you're breaking 15 volts charging, you have a regulator issue or a high resistance somewhere. Compare the voltage at the back of the alternator on the big nut to the voltage AT the battery posts.


Yes, it could be a battery but rarely. Feel if the ground cable just before the battery is REALLY hot to the touch.