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.

[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]

Originally Posted by CTScott

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)

Those are the colours I connected to on that D-shaped connector going to the left tail light, the ground is mounted under the nut/stud coming from the light CTScott.
The bulbs on the trailer are just standard trailer bulbs which work great when hooked up to my Dads 2007 Yaris. I will try and get a resistance reading as you suggested (yes it's a 4 prong plug, one being ground) when the weather clears.
Could it be a faulty converter? I've never come across one in my time but I'm tempted to buy another one to see if thats it.

[CTScott]

Originally Posted by Strider199

Those are the colours I connected to on that D-shaped connector going to the left tail light, the ground is mounted under the nut/stud coming from the light CTScott.
The bulbs on the trailer are just standard trailer bulbs which work great when hooked up to my Dads 2007 Yaris. I will try and get a resistance reading as you suggested (yes it's a 4 prong plug, one being ground) when the weather clears.
Could it be a faulty converter? I've never come across one in my time but I'm tempted to buy another one to see if thats it.

It could be a bum converter, especially if someone bought it, cooked it, and returned it. To verify you could bypass the converter and hook up the turns, and brake only. The turns will flash at an odd rate, but at least that will verify that the car drives the bulbs and if so, the converter is bad.

[Strider199]

Great idea CTScott. I'll do that this weekend.

[Strider199]

So after work I tried to hook up the converter again.

I spliced in the running lights right to a running light bulb which I checked with my tester. Plugged in the trailer and the running lights where on.
I then spliced into the left signal light and tried that. Worked great.
I then spliced into the right turn signal and it worked great.
I then spliced into the brake wire at the bulb and had my son push the brake pedal. It worked great.
Thought I was all set but then, I put on the 4 ways. The rear trailer lights flashed but they were dim. I stopped that and turned on the running lights again, nothing. I tried the left signal, both signal lights flashed dim. I tried the brakes, nothing.
I SHUT IT DOWN.
Tomorrow I will pick up a powered trailer light converter and see how that works.
Why are they making the wiring in almost every car so frustrating these days?????????

[CTScott]

Originally Posted by Strider199

So after work I tried to hook up the converter again.

I spliced in the running lights right to a running light bulb which I checked with my tester. Plugged in the trailer and the running lights where on.
I then spliced into the left signal light and tried that. Worked great.
I then spliced into the right turn signal and it worked great.
I then spliced into the brake wire at the bulb and had my son push the brake pedal. It worked great.
Thought I was all set but then, I put on the 4 ways. The rear trailer lights flashed but they were dim. I stopped that and turned on the running lights again, nothing. I tried the left signal, both signal lights flashed dim. I tried the brakes, nothing.
I SHUT IT DOWN.
Tomorrow I will pick up a powered trailer light converter and see how that works.
Why are they making the wiring in almost every car so frustrating these days?????????

Ahhh, Looking at the 2012 EWDs I see the issue - The flasher functionality has been coalesced into the combination meter, instead of being a separate flasher relay assembly.

[Strider199]

Originally Posted by CTScott

Ahhh, Looking at the 2012 EWDs I see the issue - The flasher functionality has been coalesced into the combination meter, instead of being a separate flasher relay assembly.

Ahhh, and in laymans terms that means???? Sorry CTScott, I'm not following.

[CTScott]

Originally Posted by Strider199

Ahhh, and in laymans terms that means???? Sorry CTScott, I'm not following.

It means - Yes, you need the powered converter. Integrating the turn signal driver into the cluster means saving a few dollars and that it will have less drive capability.

[Strider199]

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

[WeeYari]

Post#2 FTW.

[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.