2012 LR4 continued charging issues

[BlackOmega]

I have a couple of posts now where I have had issues with my LR4. First was a ground issue causing a christmas tree and plethora of codes to pop. I believe I have that one fixed as it has not come back. Next was a charging issue, I had noticed while watching live values after the ground issue that the 2.5 month old battery was not charging and I was getting NO battery/alternator light. I replaced the battery with a new (October 2025 manufacture AGM battery) and saw that it charged until it hit 24 minutes in then the alternator flat lined and everything ran off the battery. I just replaced the Alternator with a rebuilt Denso and it still does the same thing, it seems to draw mainly or wholly from the battery but now the alternator is not flatlined. What gives? Looking for any and all suggestions PLEASE! I grabbed the first screen cap when the battery voltage went from 14.6V down to 12.3V suddenly, then as you can see the battery steadily drops in charge % even with the alternator current rising back up. Is this somehow normal?

 

[Rover Range]

You may have a broken signal wire from the PCM.
It is the single grey wire that plugs into the alternator.

 

[BlackOmega]

So do you think it's breaking connection when the engine warms up? I assume continuity test but will that work on a cold wire?

 

[Rover Range]

The wire may have high resistance when hot.

 

[BlackOmega]

Sorry for the questions but how would I test and how would I know how much to replace? It looks like they only come in pigtails.

 

[Rover Range]

Check the resistance of the wire, from the PCM to the alternator.
I'll need your VIN to let you know what pin on the PCM.

 

[BlackOmega]

My VIN is SALAG2D40CA620895 I just got back from driving it and the voltage never goes above 12.4 except for intermittent spikes to 13 or so volts and the battery charge percentage keeps going steadily down. With all accessories including lights, brights, HVAC and whatever normally runs it never drops below 12V... if any of that matters.

 

[BlackOmega]

Forgot to attach

 

[Rover Range]

The PCM has two connectors. The circuit you're checking is in the bigger connector.
Check the resistance from Pin 95 to the alternator connector.
This is the PCM connector-looking into it.

 

[BlackOmega]

PCM is the computer behind the battery correct? Your pic is a broken link