Trailer lights questons

[mep1811]

In prepping my M416 for a trip I noticed the trailer D/S lights to be very dim when connected to my truck.

The truck's the D/S blinker and parking light are dim as well. When I disconnect the trailer the lights on the truck are back to be being bright.

What is causing this ? A bad ground on the trailer?

I look forward to your advice.

 

[dvsjw]

Likely not enough information. A bad ground would leave the tow bright and the trailer dull in most cases. You should find a volt meter and see how far the voltages are dropping and what king of amps you are pulling to light the trailer. You should not be pulling more than 5 ish amps for just lights.

1. Regulator or battery issue with the tow vehicle not being able to keep up with the added demand of the trailer. Is it a fresh modern vehicle that has seen little tampering?
2. Added resistance of a semi shorted wire on the trailer.
3. Miss wired connector. While dim do they operate in the correct manner?
4. Other things like an appliance on the trailer that may be pulling huge loads like a second battery with furnace and fridge?
5. Electric brake issues? Might check the brake controller.

What kind of plug do you have? Most small simple trailers are 4 prong flat. These should be an easy test. Some are 7 prong that support a second battery, e-brakes, reverse light and then the running and brake lights. A tougher testing process.

 

[mep1811]

Sorry here is more info . The trailer lights are LEDs. the P/S lights work fine. Just a seven pin connector no controller no reverse battery line. The trailer battery is powered on a separate line.

3. Yes while dim, they do work but dim the truck as well

 

[mep1811]

I had converted to a seven pin thinking the battery wire would charge the trailer battery . I found out that was not the case and went to a dedicate circuit .http://www.lslproducts.net/ToadChargePage.html

 

[dvsjw]

No biggie, I would suspect that somewhere when the battery charger and the 7 pin were added there was a miss wire. Were things good before the 7 pin? Or after the batt charger install?

Try...

Most likely ***Possibly double check the wiring of the battery Toad Charger.

Test the voltage at the battery and at the trailer light connector at back light. Then test the battery w/o the trailer attached. You should see little to no drop from the original voltage before the trailer was connected. If you see a big drop say from 14.5 to 10v then you are drawing too much for the system. Test the trailer by connecting a wire or jumper from the vehicle to the trailer ground. Then set up your amp meter to read up to 20 amps. Connect the red lead to the vehicle running light post and the black to the trailer running light post. Do this for each of the leads. If you test more than say about 2 amps (given you now have LED) for the lights then there is an issue on that circuit on the trailer.

The other thing that you could do is remove the bulb from all the lights (if you can with the LED's) and check for resistance between the positive and ground at the trailer plug. If you have any, then that is an issue.

The last thing to do is to trace the wires from connector to light looking for frayed insulators.

Just thoughts... Good luck.

 

[mep1811]

Thanks the toad system is a stand alone system not part of the trailer wiring. The lights worked fine after the seven pin conversion the battery and reverse wires were never connected. I am curious why it dims the truck's D/S lights as well when connected.

I'll on it today if it stops raining.