troubleshooting procedures

[elwopo]

Just got a used boat and know nothing about electrical things.

So you flip a switch and the light doesn't go on (yes...bulb is new) or pump doesn't work...etc

What's the first step in going after and fixing problems?

 

[bruceb58]

Re: troubleshooting procedures

Buy a digital volt meter, conect one end on ground and start measuring voltages at various points.

 

[Silvertip]

Re: troubleshooting procedures

Here's a basic lighting circuit but the lights can be replaced by any device such as a pump, that requires only +12 volts and ground to function. Using a test light or meter, start at the battery and measure at various points along the line working toward the device. When you lose 12 volts, the problem is between where you lost voltage and the point where you last had 12 volts. Troubleshooting gauges and other more complex circuits require a more in depth understanding of electrical circuits. In this example, if you measure 12V at the left end of the fuse but not at the right, that indicates the fuse is blown. If you measure 12 volts going into the switch but not out of it, either the switch is bad or its not turned on.

 

[Lone Duck]

Re: troubleshooting procedures

Here's a basic lighting circuit but the lights can be replaced by any device such as a pump, that requires only +12 volts and ground to function. Using a test light or meter, start at the battery and measure at various points along the line working toward the device. When you lose 12 volts, the problem is between where you lost voltage and the point where you last had 12 volts. Troubleshooting gauges and other more complex circuits require a more in depth understanding of electrical circuits. In this example, if you measure 12V at the left end of the fuse but not at the right, that indicates the fuse is blown. If you measure 12 volts going into the switch but not out of it, either the switch is bad or its not turned on.

Yup! And check all your grounds for continuity.

 

[elwopo]

Re: troubleshooting procedures

"And check all your grounds for continuity."

You bet!
(um....what does that mean and how is it done?)

I picked up a digital multimeter yesterday and will start checking things out this afternoon.

 

[Silvertip]

Re: troubleshooting procedures

To check continuity you need a meter that can measure resistance (ohms). Since the ohms function uses the battery inside the meter, you NEVER connect the meter to an energized (power on) circuit. To check a fuse for example you set the meter to OHMS and touch one probe to each end of the fuse. If the meter needle moves, you have continuity and fuse is good. If the meter does not move, the fuse is open. Checking grounds is done by connecting one probe to the ground terminal on whatever device you are checking, and connecting the other probe to the negative terminal on the battery or the ground connection at the fuse panel or ground buss.

 

[bruceb58]

Re: troubleshooting procedures

In my opinion, a better way to check the condition of a ground is to measure voltage drops in an energized circuit. Put one end of the meter on the ground of the battery and start measuring voltages going up the ground path away from the battery. You will be reading 0V if the ground has no drop.