Goner Gauges


I have a problem with dead gauges on my old aluminum fishing boat.

Last year the tachometer and gas gauges were the only two working. The speedometer, trim gauge, and volt meter did not work. As the year progressed, the tach started to stay in one place and the gas gauge stopped all together.


When looking at the connections for the gauges they are plugged into the back of the gauge except for the gas gauge which was replaced two years ago and it has wires connecting it to the boat wiring harness. I have checked and replaced all the fuses and looked for any loose connections that I could see.

What should I look for now?

Thanks for your help.


If they are all dead, it is probably a bad power or ground connection.

Using a meter of a test light you should be able to measure 12 volts between the purple and black wires on all of the gauges when the key is on.

Since this is an older boat, the speedo is probably a pitot style that works off of water pressure. Check the pickup on the transom to see if it is plugged.

Hope this helps.


Nitro Nuisance

Boat Wiring Guys,

I need your help with a 1997 Nitro 640 LX fishing boat that I just purchased.

Nitro 640LX

When I put the red/green navigation light into the plug in base at the bow, it doesn't come on, but causes one of my gauge lights to light up and stay on.

Any thoughts on where this might be going wrong?



The ground wire for the dash panel area is no longer connected. Because of this, the dash is grounding through the filament in the red/green light.

Run a test ground wire from the battery negative to any ground at the helm (maybe a gauge) to confirm.

Hope this helps



Thanks for the quick response,

You were right about the ground wire. We found and fixed that, but we have another problem now.

There is a large wire with a plug that goes into the motor that there is apparently a short in.....when we turn the ignition on, it will not do anything sometimes until you move that large wire around.

What is that wire called that plugs into the motor and apparently goes to the switch as well?

We need to figure out what to get to replace it.

Thank you,


It sounds like it is your main engine harness plug.

Most of those are modular and can be taken apart. This means that you may be able to just replace some terminals instead of replacing the harness.


Bass Boat Gauge Dimmer

Fishing Boat Wiring Guys,

I really appreciate all of the work that you guys put into your site. I'm guessing that it has kept loads of boater from doing very stupid things.

Tracker 175TXW bass boat

Here's my question...

I have a 2013 175TXW Bass Tracker and would like to add a dimmer switch to the instrument cluster lighting.

Could you tell me what color is the power wire for the lights? Or are the lights powered off the power wire for the individual gauges?

Any info would be helpful.


According to boat wiring color standards, the lights should be powered by the blue wire. But, I would recommend that you test with a meter before cutting anything.


Shiver Me Trimmer


Tonight I ran into a very odd boat wiring issue.

I have a 2002 Proline Sport 20CC with a 150hp Mercury outboard. Traveling along in the fog, my motor started to trim itself up and out of the water - all by itself! One thing I noticed is when the motor would trim up the bilge pump came on as well. (No water in the bilge, by the way)

Proline 20 CC

My guess is a common short.

What should I look for in tracing this short?



It could be a ghost. It is that time of year.

BUT, it is probably a short between the trim power wire (red) and trim up wire (blue) and bilge power wire (brow) near the shifting mechanism on your helm.

It is common for wires to be pulled tight to the shift cables. They have some movement when the shifter is actuated and eventually wear through.

Hope this helps,


Haha funny you say that. With the fog rolling in, the lack of visibility, and the boats mind of its own it was like out of a horror movie! I was waiting for a pirate ship to pull up out of the fog! Lol

Anyway I did some troubleshooting this morning and found the trim switch on the motor was passing power through it on the up side even when not depressed. Luckily the problem happened while I was troubleshooting. When I press the trim up on the motor and let go it would continue to trim up for a second before stopping.

When checking with a volt meter. Trim up pressed would pass about 12.6v and when let go would go down to 12.3v and slowly trickle down to about 11.3v. Up side was fine and passed no power if not depressed. So I disconnected that switch and only used the throttle trim switch and it was responsive and stopped without delay when I let go of the button. So it looks like a bad trim switch at the motor.

But it doesn't explain why the bilge came on too, lights and fish finder flickered when that happen also. I left the motor's trim switch disconnected so I guess only time will tell if that was the only problem.

Thanks for your help! I appreciate the quick response and assistance!!