Small Engines (Lawn Mowers, etc.): Exmark electrical problem, engine displacement, saturn auto

Question

Wiring diagram I  have an Exmark Lazer Z with a 25 Kohler Command 25 HP with an electrical problem.  My brother connected the wrong wires to the battery.  There are 2 wires that are supposed to connect to the negative  terminal along with the ground terminal wire.  He connected them these 2 wires to the positive terminal.  Of course, the engine won’t start now.  I’ve checked the battery with a volt meter and it is still ok so I don’t think the problem is with the battery.  I’ve also checked the 2 fuses.  Any ideas?  I have attached the manufacturer wiring diagram and have circled the 2 wires.  Thanks a bunch.

Answer
Hello Corey,

Hey, I understand your dilemma, I once worked on my Saturn [auto] when I was very tired and made a similar mistake.  The car just died on a hill about a mile and a half from our house.  Anyhow, based on my prior experience I would not give the battery a passing test just yet.  It is indeed probable that the battery may be showing a proper voltage but have you checked the battery with a load on.  Also I would check the individual cells of the battery, to make sure each cell is showing the correct 'Specific Gravity' reading.  Under adverse conditions a 12 Volt system needs 1 ampere per cubic inch of engine displacement.  Or stated in a different way, a 350 cubic in, [5.7 litre] engine needs a battery with a cold cranking rate of a minimum of 350 amperes.  
Voltage readings alone can not be trusted to determine the health of your battery.  My guess is, the battery is not working 100%.

To be sure run some more tests.  
Good Luck

Howard