Trailer Light Wiring Issues

[MJA1876]

Howdy yall,

I recently picked up a trailer light kit, and I've finished wiring everything up, but I've had no luck getting any lights to turn on. I've plugged in a 4-pin connection tester, and everything worked fine there.

I've got all three of the ground points (one from each taillight, one from the connector) clear of paint and attached via self tapping screws. The ground points at the front is on the trailer tongue, and was also prepped the same way. I'm not sure where I'm going wrong here.

Any ideas? Surely there's not something obvious I'm missing? All my connections (four) were made with heat shrink butt connectors. I appreciate any help.

I can post pictures if needed.

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[airline tech]

Draw a rough diagram on how you are wired.

 

[ControlNode]

What kind of lights? Incandescent, LED or other? If the bulbs are replaceable in the housing, are you sure the bulbs are installed? If they are installed and also happen to be LED, have you tried flipping them 180˚? Did you bench test them before wiring them to the trailer?

 

[MJA1876]

Each taillight has a white ground wire running from it that are both individually grounded to the trailer via a self tapper.

 

[MJA1876]

What kind of lights? Incandescent, LED or other? If the bulbs are replaceable in the housing, are you sure the bulbs are installed? If they are installed and also happen to be LED, have you tried flipping them 180˚? Did you bench test them before wiring them to the trailer?

They're the Kenwood submersible LED kit from Harbor Freight. I did not test them before wiring to the trailer. Not an electrical expert if that isn't clear already haha, just tryin my best

 

[ControlNode]

They're the Kenwood submersible LED kit from Harbor Freight. I did not test them before wiring to the trailer. Not an electrical expert if that isn't clear already haha, just tryin my best

I'm guessing you mean Kenway. Being HB goods, always a good idea to test before install. But, if you have a 9V battery and a couple nails, or if your kit included the vehicle side wiring that you didn't need since the Ranger is already 4-pin ready, you should be able to test them easy enough though the 4-pin on the trailer. It is possible the LEDs doesn't have enough load to trigger the truck's sensor that they are there, may need to add a resistor pack on which ever lead the truck test to determine if the trailer is connected. I think it's the parking lights as even with the truck parked and off I see the LED parking lights on my trailer flicker ever so often while connected to the truck.

Directions look pretty simple: https://manuals.harborfreight.com/manuals/64000-64999/64275-193175352965.pdf

 

[MJA1876]

I'm guessing you mean Kenway. Being HB goods, always a good idea to test before install. But, if you have a 9V battery and a couple nails, or if your kit included the vehicle side wiring that you didn't need since the Ranger is already 4-pin ready, you should be able to test them easy enough though the 4-pin on the trailer. It is possible the LEDs doesn't have enough load to trigger the truck's sensor that they are there, may need to add a resistor pack on which ever lead the truck test to determine if the trailer is connected. I think it's the parking lights as even with the truck parked and off I see the LED parking lights on my trailer flicker ever so often while connected to the truck.

Directions look pretty simple: https://manuals.harborfreight.com/manuals/64000-64999/64275-193175352965.pdf

That would make sense that the LED's don't draw enough power to tell the truck they're connected. So for the resistor pack, how would I go about doing that?

 

[ControlNode]

I would first confirm the lights work when manually powered at the 4-pin on the trailer, 9V battery should be enough to see that. If not, and if you have the lead for the car side, easy enough to connect to a 12V power source.

 

[MJA1876]

I would first confirm the lights work when manually powered at the 4-pin on the trailer, 9V battery should be enough to see that. If not, and if you have the lead for the car side, easy enough to connect to a 12V power source.

Alright, I tested both LED taillights and they both work, maybe a little too well (I shouldn't have looked directly into them lol). What do you mean by the lead for the car side? And connecting to a 12V power source? I rather not have to jack with the wiring on the truck, if that's what you're saying.

 

[Big Blue]

Alright, I tested both LED taillights and they both work, maybe a little too well (I shouldn't have looked directly into them lol). What do you mean by the lead for the car side? And connecting to a 12V power source? I rather not have to jack with the wiring on the truck, if that's what you're saying.

OK, when you tested the. Did you use the 4 pin connector on the trailer to power them, or did you power them at each light? You need to use the connector on the trailer that will tell you if you have a wiring issue. With using the trailer frame as part of the ground, this may be where the issue is.

 

[MJA1876]

Also, I have a spare 7-pin to 4-pin adapter. I've tested this adapter with the 4-pin connector tester, and the lights on the tester lit up properly, both running and turn signals. I've read conflicting information on if they have resistors built into them or not. I've tested the lights both with and without the adapter, and neither have worked. But from what I've read now, the problem lies in the lower power draw from the LED lights, as you @ControlNode figured.

 

[MJA1876]

OK, when you tested the. Did you use the 4 pin connector on the trailer to power them, or did you power them at each light? You need to use the connector on the trailer that will tell you if you have a wiring issue. With using the trailer frame as part of the ground, this may be where the issue is.

I used the connector on the trailer.

 

[MJA1876]

Just trying to get all my thoughts out here...would using this adapter with built in resistors add enough load to the circuit so that the truck recognizes it? Seems a little more straightforward for an electrical knowledge lacking individual like myself.

 

[ControlNode]

I saw that some of the Kenway kits included the wiring for adding to the vehicle if it didn't have a 4-pin already. I was not suggesting wiring that into the truck since the truck already has 4-pin, and 7-pin it sounds like, but instead that you could use that lead to connect directly to a 12V power source, easiest of course being a car battery. I'm not sure how you were able to look directly into rear facing lights when connection power at the connection near the tongue.

If it is a not enough load to trigger the TCM to see the trailer and activate outputs issue, that 7-pin to 4-pin with what sounds like internal resistors may work. The other option is to add a resistor to the trailer, likely on the running light circuit. But if wiring is the challenge, that adapter may be the best option.

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