Trailer light problem

[jgray]

I have a 99 LC. Was trying to take the boat out this past weekend and can't figure out why my trailer lights aren't working. I am getting nothing at the plug by my hitch. Lights on trailer are fine when plugged into another vehicle. I was not able to locate a blown fuse in the fuse box. Anyone got any suggestions??? I was unable to trace the wire as it goes up to the floorboard.

 

[TRFCSUX]

Trailer lights never work

I had same problem with my 01,Don't think PO ever used it.All i did was clean the connection,some wd-40 and a little sand paper,worked fine ever since.

 

[jgray]

After a little searching on here i see the wiring harness recall but i called Toyota customer service and gave them my VIN. and they told me the recall work was done already. I have the little 4 pin tester that lights up for each pin function (lights, blinkers, brakes, etc). I am getting nothing at all. Help guys fishing in VA is great right now and I need to be able to tow the boat.

 

[fishin]

My 99 had a blown unit (I do not know what it is called) somewhere between the plug and the fuse box. My local trailer shop fixed it for me for around $30. I also moved my plug in from under the truck to a position between the hitch and the spare tire, pointing down. This way I will not drag it off when I am off road, and it does not allow water to collect in the socket.

Brett

 

[Rugster]

After a little searching on here i see the wiring harness recall but i called Toyota customer service and gave them my VIN. and they told me the recall work was done already. I have the little 4 pin tester that lights up for each pin function (lights, blinkers, brakes, etc). I am getting nothing at all. Help guys fishing in VA is great right now and I need to be able to tow the boat.

I have a problem with my tail lights working on the trailer. All others work. I called about the recall and was told also that the work was done. I checked the interface in the wiring harness in the rear fender and couldn't see where it had ever been touched. I wonder how I test the unit and how much it costs to replace.

 

[EdsCruisin]

If you want a quick fix go to a trailer/hitch shop. They can solve it in minutes. If you want to do it right, ask the same guys about an aftermarket set up. The install takes longer, but is well worth it.

I installed an isolated system that runs off direct battery power with a relay from the vehicle lights. I put the relay in the rear, which also afforded me a full-time high amperage battery feed to the rear of the truck for other accessories. I attached a silicone sealed plug to the hitch itself in a box, out of the way of everything else. Then buy converters for different plug arrangements. The last important item is dielectric grease, which prevents corrosion and oxidation on the pins when not in use. This type of system prevents damage to the vehicle electronics when the trailer has a short. I found out the hard way.

 

[DMX84]

The ’98-‘99’s wiring harness is ButtCo. The no-longer available unit re-routed the harness up into the D-side tail light. They don’t handle shorts very well and once it see a short it no-good.
You can check if the recall was done by looking under you truck drivers’ side. There should be an oval plastic cover with a wire bundle in the middle.
If you just have the oval cover without the wires then you don’t have the new-recalled unit.
Hope this helps.
DMX

 

[DMX84]

If you want a quick fix go to a trailer/hitch shop. They can solve it in minutes. If you want to do it right, ask the same guys about an aftermarket set up. The install takes longer, but is well worth it.

I installed an isolated system that runs off direct battery power with a relay from the vehicle lights. I put the relay in the rear, which also afforded me a full-time high amperage battery feed to the rear of the truck for other accessories. I attached a silicone sealed plug to the hitch itself in a box, out of the way of everything else. Then buy converters for different plug arrangements. The last important item is dielectric grease, which prevents corrosion and oxidation on the pins when not in use. This type of system prevents damage to the vehicle electronics when the trailer has a short. I found out the hard way.

I should show some pictures of the “quick Fix” that the local shop did.

 

[mobi-arc]

I should show some pictures of the “quick Fix” that the local shop did.

Please do. I think I have the same issue, but I haven't looked into it yet.

 

[Swix]

The OEM replacment "black box" is $189. what does the "local trailer shop" do for less? just bypass the box with a inline fuse? tail lights work fine but no power for Brake or Turn. I believe I shorted the lights on the trailer, so root cause is known. but a 189 dollar fuse? What else does the "black box" do?

 

[EdsCruisin]

The OEM replacment "black box" is $189. what does the "local trailer shop" do for less? just bypass the box with a inline fuse? tail lights work fine but no power for Brake or Turn. I believe I shorted the lights on the trailer, so root cause is known. but a 189 dollar fuse? What else does the "black box" do?

I'm not sure what the "OEM Black Box" is that you refer to, but the local shop can install the isolated system, which may be an aftermarket version of the same thing. Check with a shop - I would not be surprised if parts and installation are equal to about $200 in the end. I did my own for about $100 in parts plus my labor.

 

[Swix]

black box

"TOYOTA 15 amp taillight converter auto circuit protection"
a local trailer shop offered to sell me a "kit" for 27 bucks, or a fancier module for~80.

 

[soberman001]

"TOYOTA 15 amp taillight converter auto circuit protection"
a local trailer shop offered to sell me a "kit" for 27 bucks, or a fancier module for~80.

Yeah, what he said... there are generic versions for cheap. My LC80 (1995) had the same thing after 8 years so I took it to UHaul and they did it right up. The parts are available everywhere and can be ziptied under the bumper or cross bar. Any hitch place can do it OR Pepboys.

Sometimes, they just wear out. Mine was 30k miles on the trailer when it did (145k on the LC).

 

[Swix]

Thanks!

$23.50 to be exact and a few connectors. The Toyota shop should stock this option. Done ditty.

 

[EdsCruisin]

Careful - the $23 model is not an isolated relay. It relies on power from your light circuit to light the trailer - basically a converter. The $80 version is isolated and is actually a relay which takes signals from your light circuit and uses a separate power feed from the battery to light your trailer.

I had the cheap one short and fry electronics in my van. Never had a problem with the relay version.

 

[rlabair]

Finally, Trailer lights!

Thanks to all the forum members! I finally tracked down my trailer light problem. I've got a 96 LX450, my trailer lights used to work but then some crazy stuff started happening. I would turn on my left or right turn signal and both the rear trailer lights would come on just like I had turned on my emergency flashers. So after reading the threads I cut the right turn signal wires on the Lexus black box, bypassed the box by splicing the wires and tried the lights. ALL WORKED! I now have trailer lights that work like new.

Thanks for all of the forum members sharing your experience!

 

[NMuzj100]

... I cut the right turn signal wires on the Lexus black box, bypassed the box by splicing the wires and tried the lights. ALL WORKED!

This is a workable quick-fix but without the $189 OEM "fuse" your very expensive vehicle electronics are exposed to feedback from the trailer wiring. The fact that all the Toyota boxes fail indicates that feedback from wiring is an issue. Power drain from my pop-up trailer killed a battery on my 100.

The isolated independent converter is the best long term fix. The reason a converter box is needed is to combine the brake,turn and taillight output that are separate in a Toyota wiring scheme into a combined system for trailers.

The best place to go for this kind of work is a large RV shop or trailer dealer selling large horse trailers. These guys are used to installing systems for full time use on serious trailers and will have the isolated boxes. Uhaul and similar will likely just tie into your taillights to get you through the next week.