new trailer lights do not work

randyo3629 · Post by **randyo3629** » 19 Dec 2021, 13:52

2006 polar craft trailer.
picked up the boat..the only lights that worked were the side markers on the tongue.
.
replaced the trailer harness and the rear lights with LEDs
plugged into the truck...same tongue lights were only ones on.
connected truck to another boat trailer.....all trailer lights work.

cleaned all three ground points.. shiny and tight
reconnected to truck...same result.

here's the kicker...

connected light harness straight to battery.....all lights work, with the exception being the tail lights.
bypassed all the side markers .....same result still no taillights, when connected to battery....or truck

WTH!!

i've replaced harnesses and lights before and never had this issue.
hope someone can enlighten me.
thanks

Post by **maintenanceguy** » 19 Dec 2021, 15:08

I don't know what the problem is but I would use a volt meter to check every wire coming out of the truck's trailer connector. Check the voltage to ground with the various lights on and off (tail, blinker, etc.). At least that eliminates (or proves) the truck as the problem.

All of the problems I have had with trailer brakes have been ground issues. I now just run a ground wire all the way to the tail lights and don't use the trailer frame as the ground.

MN Fisher · Post by **MN Fisher** » 19 Dec 2021, 16:36

maintenanceguy wrote: ↑19 Dec 2021, 15:08 All of the problems I have had with trailer brakes have been ground issues. I now just run a ground wire all the way to the tail lights and don't use the trailer frame as the ground.

I still use the frame - but put jumpers in at joining points...like the front-section to rear-section of the current trailer

randyo3629 · Post by **randyo3629** » 19 Dec 2021, 18:23

maintenanceguy wrote: ↑19 Dec 2021, 15:08 I don't know what the problem is but I would use a volt meter to check every wire coming out of the truck's trailer connector. Check the voltage to ground with the various lights on and off (tail, blinker, etc.). At least that eliminates (or proves) the truck as the problem.

All of the problems I have had with trailer brakes have been ground issues. I now just run a ground wire all the way to the tail lights and don't use the trailer frame as the ground.

i dont believe it is the truck. hooked up to my boat trailer and all the lights work..
just strange that the lights work the same with the new harness as with the old harness,

randyo3629 · Post by **randyo3629** » 19 Dec 2021, 19:36

i was thinking.....the marker lights in front of the tongue pivot work. the marker/tail lights behind the pivot do not work.
possibly losing ground thru the pivot?
may need to run separate grounds to lights?

GTS225 · Post by **GTS225** » 19 Dec 2021, 20:40

Did you read maintenanceguy's post from two hours ago?

YES, run dedicated grounds to all lighting. Don't rely on the trailer frame to complete your lighting circuit(s).

Roger

GYPSY400 · Post by **GYPSY400** » 19 Dec 2021, 23:36

You have a ground problem. Does the trailer pivot or bolt together behind the front marker lights? You will have to run jumper wires between the pivots/ bolted sections or run ground wires all the way back to the rear lights.

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Rumblejohn · Post by **Rumblejohn** » 20 Dec 2021, 01:02

Don't forget that LED's are polarity sensitive. If you have power to the socket, try reversing the wires. If not make sure that there are no broken wires and you have a good ground.

randyo3629 · Post by **randyo3629** » 20 Dec 2021, 22:16

GTS225 wrote: ↑19 Dec 2021, 20:40 Did you read maintenanceguy's post from two hours ago?

YES, run dedicated grounds to all lighting. Don't rely on the trailer frame to complete your lighting circuit(s).

Roger

yes i did....makes total sense.
i really think the problem has to do with the tongue pivot.

GTS225 · Post by **GTS225** » 20 Dec 2021, 23:43

randyo3629 wrote: ↑20 Dec 2021, 22:16 yes i did....makes total sense.
i really think the problem has to do with the tongue pivot.

Hence the advice from at least two people to run ground wires, rather than rely on the frame for grounding.

Roger

GYPSY400 · Post by **GYPSY400** » 21 Dec 2021, 05:56

randyo3629 wrote:
GTS225 wrote: ↑19 Dec 2021, 20:40 Did you read maintenanceguy's post from two hours ago?

YES, run dedicated grounds to all lighting. Don't rely on the trailer frame to complete your lighting circuit(s).

Roger
yes i did....makes total sense.
i really think the problem has to do with the tongue pivot.

Ahh ok, that makes sense.. run a jumper wire across the pivot, leaving enough slack in the wire that it doesn't pull the wire tight while articulated.
You can use self tapping screws to secure the wire eyelets, or drill and tap 1/4" bolts.

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