Hi Jim,
Batteries are located on the left when you are looking back into the
engine. The switch is mounted on the wall just above the batteries. I
have a 24 ft sea ray with a 250hp i/o motor. Everything worked with
the old deep cell bateries. They both just wore out. I had to keep
charging them until I decided to buy new batteries. The red cable goes
around the back of the engine to the other side and then under to the
starter I guess. Can't see it. All cables look new. Engine is very
clean. No corrosion. Maybe the selector switch went bad when I
connected the batteries backwards.. What do you think? Tried the
selector on all three positions. Nothing. The wiring is color coded.
Always turned the selector off when I was done using the boat. Even
disconnected the radio timer wire from the batteries so as to not wear
them down. Fuses on the top of the engine where many small red wire
attach are good. None blown. I pushed the red reset button on top of
the engine as well. Nothing. The old batteries were 2 1/2 years old.
Old batteries did need water from time to time but alway filled with
distilled water.
I hope I answered all your question. Thanks for all your time.
Mark