Trailer Wiring, Tow Vehicle Problem

[MichaelAnn]

I have been troubleshooting the wiring on my trailer frame (harbor freight) for a few days now, and think I finally have it narrowed down to a problem at the tow vehicle. I purchased a probe tester, and tested all of the wires coming out of the bottom of my car (Toyota Highlander). With the clamp attached to the white, the brown wire stays solid when the headlights are on, the green wire blinks when the passenger side blinker is on, and the yellow light does nothing. Good news for my trailer, since I thought the issue was my lack of experience wiring all the lights and grounding them (which I guess it still could be). I called an automotive electrician and they quoted me over $100 just for the diagnostic, then the added cost on top of that to actually solve the problem. I would rather not pay that much, and was hoping to be able to solve the issue myself, but am not sure of how to begin to fix it. Any help?

[tony.latham]

Check and make sure that both of the left turn signals (front and back) are working on your Highlander. It could be a burnt out bulb or fuse affecting your yellow wire.

Tony

[H.A.]

Ys...

[noseoil]

Always check the grounds first. Too many problems with lights & wiring to mention when 12 volt stuff starts looking for a ground to use. Don't ask how I know.....

[bobhenry]

Always check the grounds first. Too many problems with lights & wiring to mention when 12 volt stuff starts looking for a ground to use. Don't ask how I know.....

I had the exact same thing on the drivers side turn signal on my HF frame. It was a quick fix for me I clamped a screwdriver into a set of jumper cables. Grounded one end to the frame and with the other I used the now grounded screwdriver and touched the barrel of the socket and it started working. The fix was a mini worm clamp around the socket with a small gage jumper wire clamped in between the clamp and the socket and then find a good ground for the other end.

ANYONE building on a HF frame I would strongly suggest you do this worm clamp trick with all the lighting and tie the grounds to a common wire and return to the tow vehicle via the 4 ,6,or 7 way plug it will save you a lot of headaches.

[Redneck Teepee]

Always check the grounds first. Too many problems with lights & wiring to mention when 12 volt stuff starts looking for a ground to use. Don't ask how I know.....

I had the exact same thing on the drivers side turn signal on my HF frame. It was a quick fix for me I clamped a screwdriver into a set of jumper cables. Grounded one end to the frame and with the other I used the now grounded screwdriver and touched the barrel of the socket and it started working. The fix was a mini worm clamp around the socket with a small gage jumper wire clamped in between the clamp and the socket and then find a good ground for the other end.

ANYONE building on a HF frame I would strongly suggest you do this worm clamp trick with all the lighting and tie the grounds to a common wire and return to the tow vehicle via the 4 ,6,or 7 way plug it will save you a lot of headaches.

90% of all electrical problems are grounds

[Dale M.]

IN this case it has something to do with the yellow wire and its connection to internals in TV.... I have to agree with previous poster that its probably a bad connection in yellow wire or blown "converter" somewhere in TV wiring.... You need to get into the electrical and find out "how" it is wired and if there is a converter check the inputs to converter vs outputs of converter...

Might be issue of a fuse also....... Could be situation like in my Chevy pickup there is separate circuits for trailer lighting with separate fuses for trailer wiring.... Check owners manual and fuse blocks (s)...

Dale

[MichaelAnn]

Thank you for all of the input. I have definitely narrowed it down to a problem with the TV. Short of taking my car apart, I'm unsure of how to move forward without taking it to an auto electric place. I've checked the fuse, all good there.

[bobhenry]

Converters are extremely fragile electrically and are easily fried. As an ex Uhaul manager I can say the company stores are a great service bay for trailer hitch and wiring installation and you will not beat the price. They will check out the wiring for free if you are renting a trailer. So if you are inclined rent one then cancel there is no charge to cancel a reservation. ( Don't tell anyone I told ya)

[tony.latham]

Do you know if you are dealing with a factory tow package or something that was added by a previous owner?

If you can follow the wiring into the vehicle and see something like this:

https://www.etrailer.com/fitguidet1.htm Then it's an aftermarket adapter.

I'm scratching my head a bit here. The blinkers are working on your Highlander while it's untethered to the trailer, right?

And I'm liking Bob Henry's advise.

Tony

[Dale M.]

Thank you for all of the input. I have definitely narrowed it down to a problem with the TV. Short of taking my car apart, I'm unsure of how to move forward without taking it to an auto electric place. I've checked the fuse, all good there.

Next step might be to search internet for wiring diagrams for you vehicle or get shop manual, or find good online forum for you vehicle and ask questions....

Only way to find problem if you have no "signal" or voltage at receptacle on TV it to trace it back to source... Or pay to have shop do it...

Dale

[MichaelAnn]

Bob Henry, that is a great suggestion and I will surely look into it!

Tony, It is a factory installed tow package. I have looked at the etrailer diagram quite a bit. I thought about just adding a t-one connector ($34.99, easy to install) from tow ready to my car, and ignoring the factory installed connector. I am worried about messing up the electric to my whole vehicle though... as I don't know much about any of it. Does anyone know if you add a connector (directly into the tail lights) but you've got the factory installed tow package, can that damage your vehicle? The lights are all working fine on the car itself.

[Socal Tom]

Many newer vehicles are 6 filament ( Brake and turn are seperate wires) systems where as the standard wiring ( brake and turn are on the same wire) system. These systems require something to combine the signals. These can be in the factory tow package or an after market adapter.
Tom

[tony.latham]

[quote="MichaelAnn"]Bob Henry, that is a great suggestion and I will surely look into it!

Tony, It is a factory installed tow package. I have looked at the etrailer diagram quite a bit. I thought about just adding a t-one connector ($34.99, easy to install) from tow ready to my car, and ignoring the factory installed connector. I am worried about messing up the electric to my whole vehicle though... as I don't know much about any of it. Does anyone know if you add a connector (directly into the tail lights) but you've got the factory installed tow package, can that damage your vehicle? The lights are all working fine on the car itself.[/quote

I wasn't suggesting the adding of the etrailer connector, it was a thought on determining if it was factory installed or not. I think if you tried to add a connector like that, it'd still wouldn't work.

Maybe I'll nap on it and wake up with the answer.

Tony

[antilies]

Fuses, fuses, fuses.... in a LOT of cases the factory will fuse the trailer outputs separate from the tail lights. Have a look at the owners manual and find the fuses for the trailer wiring. Often these are labeled tr/Lt (TRailer/Left Turn) or something of the like. I see blown fuses all the time hooking up customers to trailers at work. (U-Haul AGM) Its all too common. If that is not the case, my money would be on a fried converter, however, this is NOT all that common on factory installed wiring packages.