# How to Test Wires



## phantomace08 (Jul 7, 2008)

When I am testing wires at the bow of my boat, what should I use a a ground? Do I hook the voltmeter to both the black and red wires or do I attached the black lead from the volt meter to some place on the boat? 

When I did some testing on the tilt motor, the instructions said to connect the red of the volt meter to the red wire on the boat. Then, it had me connect the black wire of the voltmeter to the engine block as a ground. 

I'm having trouble with my fish finder and I'm trying to figure out the right way to test it.

Thanks!


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## freyedknot (Apr 10, 2004)

connect them both to the wires bl to bl red to red. you can not use an aluminum boat as your ground. any testing on the outboard motor electrical would be with the black to the block as stated.


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## sherman51 (Apr 12, 2011)

freyedknot said:


> connect them both to the wires bl to bl red to red. you can not use an aluminum boat as your ground. any testing on the outboard motor electrical would be with the black to the block as stated.


yea. what he says. either one should work. but if you try the black wire and it dont work you can try the block. if that works then you have a bad ground wire. if the black wire or the block doesnt work then your hot wire is bad. also you can just run a ground wire off your negative side of your battery. but i would just use the ground wire you have first. unless there is something wrong with your wiring the hot wire (red) and the ground wire(black wire) should be all you need to test for juice. hope we have helped. let us know if you get it worked out or need more help.
sherman

one more thing your depth finder should have a low amp inline fuse. you might want to check it


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## Workdog (Jan 10, 2007)

Like these guys said, take your plug at the sonar, and with the multi-meter set on DC Volts (20) put the red contact on the red wire/pin and the black contact on the black wire/pin. Make sure your battery switch is on. If you get no reading, one of your wires is bad (or the fuze on the red wire is burnt out). To check continuity of your wires from the fuze box or battery to the sonar, it is helpful to have a long wire you can use as a jumper. You set your multi-meter on the ohms (resistance) setting's lowest value (ohms is also marked with an upside down horseshoe symbol). The multi-meter should be reading 1.0. Hook one end of the jumper wire to the black wire, where it connects to the battery or fuze box. Hook the other end of the jumper wire to one of the contacts of the multi-meter (doesn't matter which). Touch the other multi-meter contact to the end of the black wire at the sonar. If the black wire is good, the multi-meter should read nearly zero. If it stays at 1.0, the black wire is bad. Do the same with the red wire. Make sure the in-line fuze on the red wire (if installed) is good. Remember how to do this resistance testing of wires. It will become your most valuable tool in chasing down wiring problems on your boat.


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