I am frequently getting a battery fault light on the dash of my 03 3.0 litre.
I have read the JTIS info and confirmed that I am getting the correct voltages at the battery terminals (13.6v and 15.3v approx) using my digital voltmeters.
Using the on-board test function it appears that the PCM reads the voltage 1 volt lower than actual at the battery which probably triggers the fault light.
There are no fault codes stored.
Does anyone know where the PCM senses the voltage??? If I could find this there is probably a poor connection to be corrected.
Brian

 

Brian,

I had an 03,3.0..and it had the exact same problem...Solution: Replace the Battery cables, both the Red ones (+) all the way to the alternator and fuse box, also the Black ones(-) to body and to transmission..this is a classic problem and that will fix it.

Mostly it has been the Red one going to the Starter/Alternator that develops high resistance at the cable ends or connections at the battery terminals (noticeable by blackening or melted plastic on the cable ends...But I changed all the cables out completely to remove all doubt..Lastly, do have your battery Checked, as it too could be contributing to the issue or maybe all the problem is.