After changing my oil yesterday I started the truck and let it run for 30-60 seconds before checking the oil level. I proceeded to shut it off, checked the level and it turns out it was overfilled. It was too late to do anything about it last night, so this morning I went out and started it again, ran it for about 30 seconds so warm up the oil, and sucked out about 2 quarts with the mityvac just to be safe. Tried starting the truck again and it wouldn't start. I'm getting the typical clicking noise and low battery warnings and the truck won't turn over. The battery is reading 12.25; I would think that this is enought to start the truck. I ran a scan with the Gap tool and there are all kinds of comminucation codes. I know there are a host of things that can go wrong if you run an overfilled engine but would 1-2 minutes be long enought to foul the plugs or worse? Would trying to jump it potentially make things worse? Ultimately I was able to get readings with the engine off and after removing then adding the oil is now within normal operating level.

 

Did you get this sorted? Running overfull for a couple minutes won’t likely hurt anything, and the most common damage from running overfull (to my knowledge) is blowing out the main seals - so you’d have an oil leak. Nothing to do with the failure to start.

As for your start problem - looks like purely a battery and/or alternator issue. 12.25v is very low - probably borderline to start a car, and if it’s worn out the voltage probably drops way below what’s necessary when you hit it with a load. 12v is basically dead flat, and 12.6v is full. And those com codes are probably all due to the dead battery.

 

Yes battery's too low which explains all of the codes you're seeing, aside from starting the engine, voltage below 12.6 will cause all sorts of errors, the electrics in JLR vehicles need all the power they can get or they don't work properly.

 

Thanks for the responses. I was able to jump the truck with no issues, and after some tinkering with the oil level it turns out that it was barely overfilled. Clearly a battery issue; after driving the truck normally for a few days I used the Gap tool yesterday to clear the codes while it wasn't running, which apparently drained the battery such that it didn't start right after. After jumping it, driving for about 30 minutes I checked the battery and it measured 14.6 at idle and 12.25 while off. I checked again this morning after it sat overnight and its 12.21. Apparently thats just enough to start the truck but low enough that even minor activities without running it will drain enough so that it won't start. Guess its time for a new battery.

 

The alternator's putting out the 14.6 so that means nothing with regards to the health of the battery. There's many variables that make for a suitable battery condition, in your case it most certainly needs replacing.