I have the motor and transom assembly removed from my boat... I wanted to know if there was a way to test some of the electrical systems (ie, bilge pump, trim tabs, engine hatch, newly installed lighting, etc) without engine or transom assembly in the boat. Not sure where my ground will come from or how to complete the circuit. I have easy access to all right now and want to make sure everything is working before I install motor. I should probably know this but just want to make sure before I blow out any wiring.

Thanks

power comes from the + side of the battery, ground is - As long as the circuit completes to the battery you can run anything (provided the batterys good)

Dont they all ground back to battery negative.?

I see that the positive and negative leads for the batteries are to cables that attach to the motor... positive to the starter and neg to the bell housing. I didn't think anything would run without those being connected somewhere. With motor and transom assy installed you would just turn key to on position and then you have power to accessories... I just assumed I had to connect those cables to something. What provides the ground on a fiberglass hull if not engine and transom assembly. Maybe I am just thinking too much like a car guy.

Thanks for any insight!

Alligator clips and some wire.

When the engine is installed, there is a battery cable going from neg on the battery to the engine block - most commonly a motor mount bracket or accessory bracket. As Cole mentioned, just establish a pos and neg with the battery using jumpers with alligator clips. Just be careful to make sure it is a positive wire that you are hooking up to the pos on the battery, and not a ground. Don't want to see you fry anything.

Ultimately I was looking to check all my wiring and switches... I guess I will just have to put power and ground directly to each switch/circuit to test... thought there may be an easier way to simulate actual running situation.

Not a stupid question!! Often times the fuse panels are powered by and grounded through the engine harness. So yes, unless the harness is connected to the other part of the harness on the engine, than nothing will work!! What you could do is run a separate ground (10 gauge) up to the helm to a grounding block. Run another wire from the grounds on your fuse panels to to the block. I don't believe there is anything wrong with having extra grounds. Then testing is simple, run a jumper lead from the positve side of the battery to the positive side of the fuse panel and everything will work!!

So I guess its just all about running a line from each side of one of my batteries to the corresponding positive or negative side of the main fuse block up at the helm? Does make sense... I will give this a try and see what happens. Thank you for the help!

How did you make out?