My 2005 LR3 4.4 has finally stumped me, and I need some expert help solving this one. Car is running great, but the check engine light is still lit.

Background- On a quick errand trip I saw the battery light come on mid way. When I got back in the car to leave, it was gone, with no other/new warning lights. A few days later, the check engine light comes on, and the Torque app is telling me it's p0560, System voltage error.
So I do some checking with the multimeter. Battery getting 14.4 to it while running, about 12.7 with the car off.

So I check the fuses for the ALT, nothing. I check the ground cable from the battery, no it's looks great and both terminals are tight. I decide to see what the NAV screen says, so I check the 753 diagnostic screen and it's is showing 13.5v while running, and no DTC codes.




I finally jump on the internet and get led in a few possible directions by reading other people's posts and start to throw a few parts at the problem. Hoping it was something straight forward and since the truck has 175k miles and what looks like the original alternator, I started there.

Here is what I've done so far, to no avail-
New Denso 150a Alt
New H8 900cca battery
New brake light switch at the brake pedal
Checked the few grounds I could find
Checked fuses
Check wiring in passenger door sill (what a pain)
Check 3 wire plug going to Alt, unplugged and replugged back in to be sure.
Checked both the ECU and TCU behind battery by unplugging and looking for possible corrosion, both looked fine at the pins

Now I'm starting to think this could be something dumb/minor, that I am overlooking.








I do not own a Gap tool, but I am considering it if it will provide me a lot more info than the Torque app does. Would appreciate any insight to anything you think I might have overlooked in troubleshooting this, thanks!

Mark

 

You need the extra codes to drill down where the actual fault is, maybe someone nearby with a GAP tool can read it for you.

 

Remove and inspect the primary alternator fuse. Its in a small black box at the end of the positive power lead. I have seen corrosion inside those.

 

I have had this light come on with the O2 sensor voltage. A quick clean of the connectors on the 2nd sensors and all was good.

 

Just got resolution and came on here to post this update. Not sure how many others have seen this, or will ever see this, but this is what it was in my case.

I took my LR3 into my local LR dealership here in Carlsbad and explained what was going on. They worked on my truck for an entire week troubleshooting every possible root cause and came up empty. On the last day the senior tech who was assisting claimed he narrowed it down to this.
"Determined integrity of charging circuit and vehicle wiring ok. Identified the ECM is not providing ground for C0635L-54, internally shorted. Recommend replacing ECM. Customer declined"

So since I was out of options, I decided to try Precision ECM in Illinois since they had good reviews. It was basically a hail-mary/last ditch effort by me hoping that the LR dealership was actually right. I pulled out my ecm and sent it to them and by the end of the week I had a reconditioned OEM ECM returned to me that had been flashed with my original ECM's programming. They claimed it was 100% plug & drive since the car would see it as my original ECM. It also carried a full warranty if it wasn't as described.

Long story short, that's exactly what it was. After the install my LR3 fired right up and ran perfectly with no codes showing and no CEL. If I was a religious guy I would claim it was divine intervention. The cost of the swap was $600

Thanks for the input everyone