Ground wiring question for wood lightbar

[Thorne]

I've rigged up a wooden crossbar made from cheap ply painted white and plastered with reflectors, reflecting tape, a CAUTION sign in the center and trailer lights at each end.

The light bar is attached to a vertical post with pintles that fit on the gudeons on my dory skiff's transom, with the rudder keeper also keeping the light bar in place. The wires are strung down the middle of the boat when trailering, and the whole assembly is removed before launching.

http://pic80.picturetrail.com/VOL1001/4000928/8302360/314588303.jpg

But trailer wiring harnesses and lights are all designed to be grounded to the metal body of the trailer, and I'm having problems getting the lights to work correctly.

I have a test probe with light and have confirmed that all the functions at the plug are working - L turn blinker, R turn blinker, running lights, brake lights.

Should I run the ground wire from the plug to each of the lights directly, and if so, where do I split the ground wire (there is only one coming off the plug)?

An alternate would be to run a strip of metal plumber's tape across the back of the light bar to each of the lights. I could ground each light to the metal tape, then run the ground wire to the center of the tape.

Any other ideas?

[Gary E]

If you have it wired correctly you probably have a bad ground.
To find that bad spot I would use a test light. If you dont have one, make one from a wire, an icepick and a lightbulb. Make the wire long enough to ground on the battery terminal of the car and reach the farthest point. Start probing and you will find where the voltage stops lighting the bulb.

[Thorne]

Thanks, Gary.

At this point I've got the ground wire split and running to both lights. Actually I stripped part of the insulation off the wire running to one light, wrapped the end of the copper wire from the other light around that bare area, then taped the whole thing together to make a "Y".

But I'm wondering if using a metal strip / plumber's tape across the back of the light bar might 'balance' the ground better? I could run the 'main' ground wire to the center of that strip, then ground both lights to the ends of the strip.

Replaced one of the lights last night that wasn't working correctly, but can't find any inexpensive ones that have a separate ground wire -- the cheap ones ground through the two mounting bolts in the back. Will test tonight.

[Tylerdurden]

Just bond the lights together with wire and tie your ground to that.

[Thorne]

Tried that. Should the ground wire attach to the middle of this bonding wire, or at one end where one of the lights attach? I had it attach at one end...

As is often the case with electrical setups, I'm chasing multiple issues on this light bar, but replacing the lights and ALL wiring should fix those...hopefully!

;0 )

I really hoping that I don't have to purchase a powered converter for this. The length of the wiring is under 20' but necessarily has several splices on each wire (one near the plug and one at the light). May have to get the voltmeter out -- damn!

[Gary E]

Voltmeters are decent to show you that "some" voltage is there... But they are louzy showing that ALL of it and CURRENT is there.... Make the Icepick tester.

[Tylerdurden]

if you have metal cased lights drill out a rivet holding the lamp socket and make your connection there. Some of the Chinese housings don't work out of the box.

[davidagage]

Thorne, I think you have them wired wrong. The brake and turn should be the yellow and green and the brown is the tail lights. By tie-ing the brake and the tail lights together you have your flasher all confused...
Then just split the ground and run it to each light.

I think..:cool:

DG

[Thorne]

Nope, I managed to avoid that particular pitfall (fell into nearly all the others, though) == the plug's green wire goes to the green wire on the R light, brown wire likewise -- they are not joined at all. Ditto for the yellow wire for the L light.

The brown tail-light/brake wires come from a common source on the plug, with the brown wire splitting into two, one for each tail light.

http://www.accessconnect.com/images/4%20way%20wiring.jpg

[davidagage]

Nope, I managed to avoid that particular pitfall (fell into nearly all the others, though) == the plug's green wire goes to the green wire on the R light, brown wire likewise -- they are not joined at all. Ditto for the yellow wire for the L light.

The brown tail-light/brake wires come from a common source on the plug, with the brown wire splitting into two, one for each tail light.

http://www.accessconnect.com/images/4%20way%20wiring.jpg

This dosn't match your description.
yelow is brake & LT
Green is brake & RT
Brown is parking (tail) light only

Up top you say that the brown is brake and tail

The trailer may be right. How is it tied into the car?

[Thorne]

Sorry, my drawing is incorrect, the above illustration is correct.

The brown wires are the same for both lights -- this is the same on most small trailers. That means running lights, dimmer than turn or brake.

The green wire R and yellow wire L do turn signals and brake -- the brighter lights.

That's the way it is wired up, I used correctly colored wires to extend the harness so there'd be no confusion at the back end.

Ground is a white wire, and the main change I've made from the above diagram (for the trailer) is to run it all the way to the lights as I have no metal frame to ground to.

[dredbob]

Thorne,

I've had similar troubles in the past. I also built a light bar to hang on the back of the boat. My white wire goes from the connector to one light, then across to the other light. I use a Y-connector to power the light bar and the trailer lights. I also run a white ground wire on the trailer itself, in addition to grounding to the trailer. By this I mean I run a redundant ground wire from the connector to each light on the trailer, so I don't have to depend on a path through the trailer.

I've had so many problems with trailer lighting in the past (usually the tail light/brake combiner/convertor boxes going bad) that I have built test rigs for the trailers that do not involve the tow vehicle, as well as buying a little test box for the vehicle circuits. I also wired my vehicle so that the tail light convertor box does not stay attached except when actually being used.

Bob

[StevenBauer]

I can't remember how I wired the ground on mine. I'll check after supper.


Steven

[Tylerdurden]

Its all about bonding.

[JimJ]

All the trailers I have wired have a separate earth wire (white) to each lamp. This wire leads back to the trailer plug.

The other colours with plug numbers are;
1. Yellow - LH turn lamp (amber lamps
2. Black - Reversing Signal
3. White - Earth return
4. Green - RH Turn lamp (amber lamps)
5. Blue - Service Brakes
6. Red - Stop Lamps (Red lamps)
7. Rear, Clearance and Side - Brown (Red rear lamps, red/amber side lamps)

Using the trailer frame for earth return leads to more problems than it is worth.

JimJ