PM me the serial number of the truck, I will get all the factory info on it. More than likely the cables leaving the battries end up together @ the starter. I work @ F/L dealership.

 

I've owned several N-14 Cummins equipped trucks. Those engines are bulletproof. They are cold natured, so I always plugged mine in under 32°. It's not necessary, but they will run like a 3 cylinder until they warm up. In real cold temps, I'd use a snort of starting fluid to get her going if I couldn't plug her in.

I would stay with 4 batteries, but 3 is sufficient. I would get a separate bank of deep cycle batteries hooked through an isolator for running an inverter when shore power isn't available. The isolator will keep this bank from drawing down the starting batteries.

Guardrail

 

Ran many a L10 and M11. Fleetguard filters and Chevron Delo 400 oil. 2000 doesn't require ultra low sulfer diesel and thus doesn't require the low ash oil. Get the CI-4+ (Delo 400) spec instead of CJ (Delo 400LE). The CI-4+ has zinc which is an amazing lubricant. I got 25-30,000 miles out of every oil change (oil analysis came back as still usable) and got 750,000-800,000 miles on them before they were traded in.
Replaced many injectors, but still got at least 300,000 miles out of 'em. Most common problems were gasket and o-ring leaks from age and dry rot. They were very reliable engines. I think I only replaced two turbos and one was only because it was 13 years old and when I pulled it off to do exhaust manifold gaskets the oil drain pipe flange was too rotted to get a good seal if I reused it. Again, very low maintenance, low operating cost engine.

 

coming from a kenworth mechanic standpoint. they're very solid engines. I've seen the jake brakes gum up (due to lack of maintenance) i'm not sure for rv's but as far as over the road trucks the oil has to be sampled every year to see what kind of metals are in it. it'll give you an idea of what kind of shape the bearings are in, whether there is excessive fuel in the oil, traces of coolant, and any other materials.

Heres a pretty good place to do an analysis: https://www.cashmanequipment.com/Flu...FdFcMgodBSsAeg

I'm not too sure where we send ours too, but this might be a good place to start.