Check your voltage from the ground where you are reading 7.5 volts to the actual ground (truck chassis). Sounds like a floating grounding. It should be in your connector. If you have 12 volt on the hot then your probably have 4.5 volts on the negative which means you have no negative to ground but is back fed through the ground to another part of the ground circuit which is usually lights but not with LEDS so perhaps the backup device or license plate bulb. Bottom line: no solid ground to the vehicle.
I think you need to sell the boat and trailer. Give me a call, I'm sure we can work something out.....
wtf, everything's new. I go with the floating ground issue. I got burned by that a couple of years ago. My meter ground connection just wasn't making a 100% connection to the trailer ground connection.
It could be a floating ground but i am checking the + AND - of the wires going to the lights. Only reason i can think of a floating ground is if the trailer is actually grounding through the hitch on the truck.
I had the lights pluged into the truck but not the hitch
Originally Posted by mmandley
Someone can correct me if I'm wrong, but I think one of the connector leads pushes the ground through to the trailer. Then on the trailer end that same lead will eventually connect to the trailer frame, which is used as ground and one terminal of each light fixture connects there. So even with the hitch not connected the appropriate voltages should be found on the trailer.
I'm thinking the connector's ground wire is either poor (high resistance) or non-existent and the hitch doesn't help either way. Running all LEDs there is very little current flow so any type of ground should work as there would be no voltage drop along the ground circuit. Those electrons are lazy and found an easier way back home than through the ground wire.
Looked as this again last night after work, its been a hard week, sun and 75 almost every day and i get home so late i cant work on the trailer.
Last night i unhooked the burned out LEDS from the MOOMBA etching and still same low voltage. This morning im going to go in the tongue where all the wires split and start testing in there, see if i can fine the voltage drop point.
When testing the various points within the trailer circuits, use BOTH the vehicle ground (with a heavy jumper) and trailer ground as a reference.
I worked on this yesterday and this is what i found out.
I have 12.3 volts from my truck plug.
I have 12.3 volts through the 7 pin to 5 pin adapter from Boat Mate
At the 5 pin it has 2 of each wire molded in,
2 Brown < running lights >
2 White <ground>
Several others for the tail and turns < not important >
Checked voltage out of that plug and everything was 7.5v
What i first did was unplug the License plate light as this is a 194 bulb not an LED BAM instantly my LEDS got real bright again. So i thought i found my problem. Checked my Voltage and it was now 9.5 up 2 volts from where i started.
I then started checking each light thinking i might have a shorted LED light. Each light has a small LED board inside.
Each time i disconnected a maker light my overall voltage increased .25
By the time i disconnected all my LED marker lights i gained 2.25v for a total of 11.7 V
Only thing connected was the tail lights, i disconnected them and had mt 12.3V
I reconnected each light and checking the voltage each time and it was a consistent drop so no big deal i guess.
And once i had everything done, i plugged the Etch Lighting LED bars in and they worked again. They were showing burned out but now they work.
IDK i talked to the Dealer and they are stumped as well. All i can think is this has something to do with the daisy chain effect of how the trailer is wired from the factory.
Unlike cars, nothing is home ran to the 12V source.
Absolutely predictable as the wire and connector resistance becomes more of a loss issue with greater current draw.
If you do a dedicated circuit with its own disconnect and heavier wire gauge you can eliminate almost all of the voltage drop.
Yea i was thinking this might be the way i have to go with it. Run a line right up the inside of the trailer frame like the factory is, then tie it into the main hardness at the voltage source. I was just hopping this project would have been more plug and play not so much design an entire setup lol.
Originally Posted by EarmarkMarine