Trailer hitch wiring yaris 2012

[Strider199]

I was going to post this in the electrical section but this is a problem with a new 2012 Yaris.

This past week end I used my multi-meter to find which wire goes to what in the left rear tail light connector after I removed it from the socket.
I was happy to find, running light, brake light, and left turn signal. I used the fast splice connectors to attach the wires from the 5 to 4 wire converter. I than found the right turn signal in the right rear tail light plug. I was done. I used the multi-meter to check the power out put on the plug which goes to the trailer. Everything seemed fine. As a note, the ground is fastened under the screw to the tail light which seems like a strong ground.
I hooked up the boat trailer harness and turned on my various lights.

Not a glimmer. After disconnecting the car from the boat, I got my 12 volt battery out and using a couple of leads, I tried each wire plug on the trailer. Each test on the trailer lights was successful. I also re-tested the car plug and found only 4-5 volts coming from the taillight.
After the key had been out of the ignition for 5 minutes, the voltage was back to 12 volts on all plug connects in the car.
After double checking which wire gets power from what circuit and finding every plug connection was ok, I tried again to power up the trailer lights same result.
Back to the drawing board.

[WeeYari]

Sounds like you need a wiring harness which takes a direct power feed from the battery.

[Strider199]

Originally Posted by WeeYari

Sounds like you need a wiring harness which takes a direct power feed from the battery.

Well I finally found a tail light converter which has the capability to be wired directly to the battery's positive terminal. I ran the 12 volt positive wire from the battery, under the vehicle zipped tied to the brake lines all the way back to under the spare tire. Then I poked a hole in one of the rubber grommets in the hatch floor and into the Reese powered converter (#78104). Hooked up the rest of the harness and tried it out.

It all works!
Thanks WeeYari and CTScott for the assistance.

Note, the ground at the left tail light isn't the best. I used one of the studs coming from under the hatch floor as a ground and the voltage stayed true.

[CTScott]

You need a trailer wiring converter. It won't require any additional wiring from the taps that you already did, but it will properly isolate the trailer lights from the car's lights, preventing the voltage drop.

[Strider199]

Thanks for the suggestions Guys.
I do have a similar wiring converter installed CTScott, it's not a Hopkins but has the same extra brake wire lead which is needed because of the separate signal bulb.
I was really hoping it wasn't because I needed a separate power supply due to draw WeeYari but it does sound like something is shutting down due to a lack of power.
Next chance I get I'll run the converter to the larger main bulb wires instead of those hair like wires from the main plug and hope that solves it.
Any other suggestions are welcome, please.

[CTScott]

Originally Posted by Strider199

Thanks for the suggestions Guys.
I do have a similar wiring converter installed CTScott, it's not a Hopkins but has the same extra brake wire lead which is needed because of the separate signal bulb.
I was really hoping it wasn't because I needed a separate power supply due to draw WeeYari but it does sound like something is shutting down due to a lack of power.
Next chance I get I'll run the converter to the larger main bulb wires instead of those hair like wires from the main plug and hope that solves it.
Any other suggestions are welcome, please.

If you are running the converter, but still seeing the voltage drop, then you are probably exceeding the current capability of the module and/or flasher relay. Are your trailer lights LED or bulb?

[Strider199]

The trailer lights are bulb. Duel elements, running lights and brake/signal.

[CTScott]

Originally Posted by Strider199

The trailer lights are bulb. Duel elements, running lights and brake/signal.

Bulbs definitely draw more current, but unless someone installed some crazy wattage bulbs, the converter should have taken care of the issue. Can you take some resistance measurements on the trailer connector to see what you measure for each of the three pins to ground (assuming you have a 4 wire connector)?

Also, to verify your wiring, one the 2012 tail light connectors:

Taillight - Green wire on either right or left
Stop - Light blue wire on either
Right Turn - Sky blue wire
Left turn - Yellow wire
Ground - White/black (or bare metal bolt connection)

[Strider199]

Thanks for the translation CTScott. I'm feeling a little more confident now.

[WeeYari]

Post#2 FTW.