Wiring Tail lights-right is dim

[Capebuild]

Hello,

I'm testing my wiring set up in preparation to run the wire for the tow vehicle to trailer lighting. I'm using a 7 pin connector from TV to trailer.

One issue: The tail lights (Grote lights) have 3 contacts. For the left tail light I've hooked up the red to red, the white to white and either the green or the yellow to the black wire on light provides the brake light and the turn signal. Not sure why both the yellow or green provide the turn signal, but I'll use the yellow. The light is nice and bright. So all seems well with that light. However with the right tail light (red to red, white to white and brown wire to the black wire on light)..... the light intensity is no where near that of the left light. Any suggestions as to what might cause this difference?

Thank you for the help!

John

[Pmullen503]

Using a test light and/or volt meter, verify that you are getting what you should from your trailer harness:

º White Ground.
• Brown Taillights.
• Green Right turn / brakes.
• Red Auxiliary power.
• Yellow Left turn / brakes.
• Black Reverse lights.
• Blue Electric brakes.

If not, the vehicle or harness is wired wrong. Your colors seem wrong on your trailer harness.

Check that your grounds are good at the frame and the lights.

Then do your connections to the tail lights.

[QueticoBill]

you might swap wires temporarily left to right and see if dimness goes with or stays. Should be easy and could eliminate a lot of possibilities

[QueticoBill]

you might swap wires temporarily left to right and see if dimness goes with or stays. Should be easy and could eliminate a lot of possibilities

[Capebuild]

Thanks for the help and suggestions.

I'm just in the "testing" phase...so nothing is really hooked up yet. I had used the same tail light to check both the right and left turn signals. For some reason the right turn function was dimmed. First I need to tighten up the wires that are connected to a junction box I installed. I had just hand tightened the connecting screws, so maybe I'm not getting a good connection. I'll try again tomorrow. I'll report back if still having issues.

Thanks again.

John

[pchast]

Its often a bad ground connection, unless
you have the brake and tail light switched.

[Squigie]

Incorrect wiring and/or bad grounds are the primary causes of dim lights.
Bad solder joints and/or improper voltage come next, if they're LED.

[Capebuild]

Thank you all for the help.

Kind of a frustrating experience with these light hook ups. One thing that I realized is the 7 pin connector I installed does not seem like it has a typical wiring layout (image attached). So this may be resulting in some incorrect wiring hook ups. I did get the marker lights and license plate lights to work as they should using the white wire to white wire connection on the fixture along with the green wire from trailer to black wire on fixtures. They illuminate when the car's lights are turned on.

As I read somewhere, test by function not by wire color.

I tested each wire coming from the 7 pin plug to the wires that terminate in this junction box where the wire ends reside and all test positive for continuity. I think I just need to methodically test each fixture at the cars plug (bypassing the trailer for now) and see if I can get some satisfaction from each fixture, then I can figure which wires I need to connect to that come from the trailer. You think there'd be some formality to the way these plugs are wired up and manufactured. Learning as I go.

[western traveler]

John,
I just went through the same frustration. It was a hair pulling experience.

Two problems I encountered. My TV is an “03” Ford F150

1. Didn't have enough current to make the LED flashers work. I added dummy load resisters which would work for about 2 minutes but the flasher module still wasn’t strong enough to operate them continuously.

2. And what seems to be true 99% of the time I also had a bad ground in my TV 7 pin which wasn’t that old. I figured that out when I ran a ground from my trailer block to the TV frame.

In my case I ordered a new 7 pin TV plug (that plug is two parts, the pins are separate from the front and that was where my problem was).

I then I replaced the taillights with incandescent tail lights. I didn’t want to have to tear into the dash right now to change out the flasher module.

[Capebuild]

ARGGHHH!! What a Cluster F of an experience trying to figure this out. Again, I don't really get why the wiring of these connectors are not standardized so all wiring set ups "speak the same language".
So all the wiring colors correspond with one another.

Finally got it though. What I did was just hook up the lights directly to the seven pin connector on the tow vehicle, bypassing the trailer. Determined which connectors provided the correct functions to the lights.
Then paired up those connectors with those on the 7 pin connector attached to the trailer's wiring. Forget about the wire's colors, just matched up the functions. In the end, all worked well. As an example, the left tail light and left turn signal wound up using the white to white wires (ground), the green trailer's wiring to the black wire on the light, and the red trailer's wire to the red wire on the light.... worked. For the right turn signal/ right tail light..... white to white (ground), green trailer wire to black wire on light and brown trailer wire to red on light... worked. The thing that made all clear was testing each individual light directly to the tow vehicle's 7 pin and relating that all to the 7 pin connectors on the trailer's wiring. Again... forget about the wiring's colors. Got the marker lights and license plate light to work as intended... even got the 3rd brake light to work as intended. All of these are LEDs.

A frustrating experience to say the least but got all to work. Smile.

John

[pchast]

Good work! I can imagine the stress and frustration.

[Tom&Shelly]

ARGGHHH!! What a Cluster F of an experience trying to figure this out. Again, I don't really get why the wiring of these connectors are not standardized so all wiring set ups "speak the same language".
So all the wiring colors correspond with one another.

Finally got it though. What I did was just hook up the lights directly to the seven pin connector on the tow vehicle, bypassing the trailer. Determined which connectors provided the correct functions to the lights.
Then paired up those connectors with those on the 7 pin connector attached to the trailer's wiring. Forget about the wire's colors, just matched up the functions. In the end, all worked well. As an example, the left tail light and left turn signal wound up using the white to white wires (ground), the green trailer's wiring to the black wire on the light, and the red trailer's wire to the red wire on the light.... worked. For the right turn signal/ right tail light..... white to white (ground), green trailer wire to black wire on light and brown trailer wire to red on light... worked. The thing that made all clear was testing each individual light directly to the tow vehicle's 7 pin and relating that all to the 7 pin connectors on the trailer's wiring. Again... forget about the wiring's colors. Got the marker lights and license plate light to work as intended... even got the 3rd brake light to work as intended. All of these are LEDs.

A frustrating experience to say the least but got all to work. Smile.

John

Glad you figured it all out John! I bought a bunch of different color heat shrink (on Amazon) then went and put some on each end of each wire, with whatever color code I decided was "my standard". Then to heck with the color of the wires.

Tom

[western traveler]

[quote="

Glad you figured it all out John! I bought a bunch of different color heat shrink (on Amazon) then went and put some on each end of each wire, with whatever color code I decided was "my standard". Then to heck with the color of the wires.
Tom

Tom,
That’s a great tip. Easier than trying to keep tract of the piece of paper I have misplaced twice since figuring it out.
Ralph

[swoody126]

as mentioned above the GROUND is usually the culprit

however any connection that is not sound/firmly made is a potential culprit

everyone who owns/tows a trailer of any kind needs a circuit tester

these tools resemble an ice pick/awl with a clear plastique handle that has a light bub in it and a pigtail coming from the end of the handle w/ an alligator clip on the end of the tail

OIP.o7HiZfwP1ClCKZwWK6nKmQHaHa.jpeg (5.15 KiB) Viewed 453 times

these tools can be had from virtually any/all sources selling automotive/agricultural/general tool suppliers

HF, TSC, Oreilly, NAPA and Amazon ...

connect the clip to any known ground and touching a contact point or bare wire will light the bulb in the handle

you can even prick thru the insulating wire cover to the wire to verify a circuit

John you have resolved your issue for now butt you still need one of these tools and for less than $10 you aint gonna miss any meals to have one in your kit

now label both ends of each wire since your color scheme doesn't match any other's ;-)

sw

[Capebuild]

John you have resolved your issue for now butt you still need one of these tools and for less than $10 you aint gonna miss any meals to have one in your kit

Thanks, swoody126. Appreciate the tip. By coincidence when I was in Harbor Freight last week I actually picked up one those. Haven't had an occasion to use it yet, but sure it will come in handy at some point.
Been using my multi meter quite a bit and that has cleared up quite a few issues

Thanks again.

John