Trailer has working running lights, no brake lights or turn signals

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HoosierHacker89

Seaman Apprentice
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Feb 5, 2024
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35
My boat trailer seems to have working running lights, but the brake lights and turn signals are not working. I hooked my vehicle up to my 5x8 utility trailer to see if I had a vehicle or trailer issue. I have working running lights and brake lights and turn signals on my 5x8 utility trailer.

I replaced my wiring harness on my boat trailer for good measure and I took a wire wheel and make sure I had good clean contact on my ground. Advice on what to check next?
 
C

cyclops222

Commander
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Mar 21, 2024
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2,441
The light bulbs or LEDs are burned out. Or corroded. connections at the light fixtures. Might need new fixtures if you back in deep enough to submerge them.
Salt or fresh water ?
 
dingbat

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,505
Ground issue…..turn signals and tail lights require a much more robust (clean) ground due to the power surges.

You need to clean the grounds on the individual fixtures.
 
dingbat

dingbat

Supreme Mariner
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Nov 20, 2001
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cyclops222 said:
Power surges with LEDs ? How much.
Click to expand...
Why not?
Switching (on/off) inherently causes transients.

How much depends on the wattage of the LED and the use, or lack of, an effective suppression scheme in the circuit
 
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cyclops222

Commander
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I did some research on inrush current ratios. Some can be as high as 100. Thanks for the education. (y)(y)
 
ESGWheel

ESGWheel

Senior Chief Petty Officer
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Aug 29, 2015
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727
Has the issue existed since the new wiring harness installed?

I am assuming it’s a standard 4 pin type and you are using the trailer frame as a ground. If yes, here is one simple check with the trailer plugged in: using a multimeter set to Ohms and put one probe on the vehicle and the other on the trailer in locations where there is a known good ground. Does it read close to or at zero Ohms? If not, your ground wire on the new harness is not making a good contact with the trailer. If yes, further troubleshooting required.
 
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