I'm looking at a No. 12 (80C) 24 volt direct start grader.  The 2-12 volt batteries are connected in series to a Positive ground.  I know that IH tractors were often positive ground but I haven't run across a positive ground Cat.  BTY; the grader started with a little ether but I couldn't tell if it was charging or if the glow plugs worked.
Is this polarity normal for the 80C grader?
 

Hi, Delta KJ.
If it izza positive ground, it will be the first one I have heard of. The English seemed to be big fans of positive ground systems way back when but American firms not so much.

That said though, if your system was an after market installation, that might be a whole different ball game.

Just my 0.02.

New or after market it should be Negative ground.

typically most things are negative ground.
the british and some japanese vehicles were positive ground and switched earth. one side benefit is switches last longer(less arcing). word of warning! some jap vehicles were weird in being negative ground but the switch was on the ground wire not the power wire as normal everywhere else in the world.

the only thing that cares if its positive or negative ground is the voltage regulator and the alternator/generator. everything else will work just fine either way. (note the generator can be repolerised to neg or positive ground.)

to check if its charging use a volt meter take a reading at idle then increase engine revs the voltage should also rise do this test just after starting as the charge will be low and the reg will be allowing charge provided its not knackered.

there is no problem with it being positive ground.

you just need to remember that it is when working on the electrics.