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Author Topic:   Trailer lights not completely working
eportfolio posted 03-22-2008 06:58 PM ET (US)   Profile for eportfolio   Send Email to eportfolio  
I just bought the STS LED trailer lighting package at Boater's World. It has 2 rear lights and 2 side marker lights. After removing all of the the old lighting and wiring and re-installing the new I tested the lights. Rear blinkers work, rear lights (when headlights are on) work, brake lights work, but the license plate light and both side marker lights are not working.
Any thoughts why these three lights aren't working? The only thing I can think of is to clean the ground connections, but other than that I have no clue.
Any help would be greatly appreciated.

Thanks, Jim

deepwater posted 03-22-2008 11:14 PM ET (US)     Profile for deepwater  Send Email to deepwater     
getting the contacts clean is a very good place to start,, after that an ohme meter will help determine if you are getting power or have a good ground
Jerry Townsend posted 03-22-2008 11:24 PM ET (US)     Profile for Jerry Townsend  Send Email to Jerry Townsend     
Since both side marker and license plate lights are not working - the problem is upline - something that is common to both / all lights. The problem is not with the individual light sockets. --- Jerry/Idaho
Doug Mac posted 03-23-2008 07:57 AM ET (US)     Profile for Doug Mac  Send Email to Doug Mac     
I had similiar problem with side lights. Ended up running a ground wire from each side light to SS screws drilled into the frame.
eportfolio posted 03-23-2008 10:00 AM ET (US)     Profile for eportfolio  Send Email to eportfolio     

Thanks guys! I went ahead and drilled out screw holes into the frame and now the markers work, BUT when I tested the lights further I noticed the following:

With headlights off: brakes work, turn signals work, markers off (normal), rear side lights off (normal), license light off (normal).

With headlights on: brake lights don't work, license plate lights don't work, markers on, turn signals don't work.

The strange thing is that the only thing that doesn't consistently work is the license plate light. Everything else works with the headlights off, but not with them on.

When Uhaul installed the lighting package at the car, the connector they installed has lights that light up to show what the controller in the car is doing. With the lights on and the turn signals on in the car, those "test" lights at the connector are on and blinking indicating that both are working, but they aren't working on the trailer. So it must be a problem at the trailer...

Any more thoughts?

eportfolio posted 03-23-2008 10:02 AM ET (US)     Profile for eportfolio  Send Email to eportfolio     
I didn't mention that I drilled out holes in the frame and re-screwed grounds into frame at all 4 lights (2 side markers and 2 rear lights).
eportfolio posted 03-23-2008 10:44 AM ET (US)     Profile for eportfolio  Send Email to eportfolio     
Phew! Figured it out.

After taking some more time to examine the trailer, I noticed that the center rail and the side rails of the trailer are bolted, not welded. So I cut a couple of new ground wires, drilled more holes in the frame and connected them across all three sections of the trailer frame.

That corrected the problem. The bolted connections in the frame had corroded and jeopardized the continuous ground in the frame and wiring.

Thanks for all of your help guys.

Chuck Tribolet posted 03-23-2008 09:16 PM ET (US)     Profile for Chuck Tribolet  Send Email to Chuck Tribolet     
Eportfolio: A search here indicates that you have a Montauk.
The odds are real good that your trailer is over 80" wide.
Put a tape measure on it. If it is, you need different lights.

- You need a set of three lights as high up as possible. On
a boat trailer that means on the rear cross member. That's
not very high up, but it's as high up as possible. These are
called "over 80 lights".

- The tail/brake assemblies are different. I think the main
difference is that they shine a red light to the outside too.


swist posted 03-24-2008 09:34 AM ET (US)     Profile for swist  Send Email to swist     
After reading about a bazillion trailer light problems across many boating forums, the number of times the problem is a bad ground is significant. If I designed my own trailer lighting system I would simply run two wires each light. How much more could it cost? Relying on some half-corroded galvanized frame with rusty bolts for electrical continuity just doesn't make sense.

And experience from all these problem reports shows that grounding problems often manifest themselves with real weird symptoms (the left brake light only works when the radio is on and cousin Earl is sitting on the trailer, etc etc). The time spend fooling with all this cannot be worth it.

jimh posted 03-24-2008 09:49 AM ET (US)     Profile for jimh  Send Email to jimh     
To promote better electrical contact between a chassis and a terminal connector, a device known as a star washer is often used. The washer is designed with small protrusions that will penetrate the chassis (or trailer frame) in order to make a good contact. However, on a galvanized trailer, they might make tiny breaches in the galvanized skin, and that could promote rust.

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