Wiring at rear for brake, and running lights.

Hi all-

Just finished putting a trailer hitch on my '03. Now need to wire in a 4-way plug for lights.

Does anybody know the details of the rear wiring harness (wire colors vs function)?

 

Check Amazon for plug in wiring harness for Tacoma.
It has the module.

 

There’s a plug and play curt harness for like $30. Do that, stay legal

heck, for another $10 or so you can get the round plug option like I did and run a charge leg back there

 

what the previous two posters have said, there is a plug'n'play solution from a few vendors that require no splicing or wiring, just a screw on the frame for the ground wire.

https://lmgtfy.app/?q=2003+tacoma+trailer+wiring+harness

first option:

$51 Hopkins Towing Solutions 43315 Plug-In Simple Vehicle Wiring Kit

https://www.amazon.com/Hopkins-43315-Simple-Vehicle-Wiring/dp/B0002Q7ZKK

 

Townships need ticket revenue go with not having turn signals !!

If you get a officer having a bad day and he puts your vehicle out of service things can get expensive.

 

I have been through 2 of the curt harnesses. They seem to last a couple years then get some kind of an internal short and you don't get tail lights but the brake lights still work. I just remove the harness and put a new one in. I bet others on here have had the same situation because I think it is a know problem with these. I don't have any better solution as I tried to find a higher quality harness but could not.

 

yeah the cheap diodes or whatever inside usually go bad in our northern regions. maybe not so much in the southern dryer climates but I've had 3 or 4 so far on mine

 

Some time ago I bought something like that of Amazon and installed in my truck. The plug'n play is great as I could use the "extension" to plug additional things (backup camera, camper stop light), without splicing into original wires. I used it only once for towing when I rented a wood splitter from Home Depot. After that I bough 5th gen 4Runner with factory installed trailer connector, and Used this truck for towing stuff.

In Poland the 4-wire trailers are not legal, so the module is useless for me but it is still working and not causing any problems in electrical - and I have it almost 10 years now.

Now looking back I think that these cheap adapters are dumb. Bulbs in trailer are using original wires, switches and fuses from truck's lighting. Any short in a trailer will blow the fuse in the truck. All trailer adapters available in Poland connect to vehicle lighting only to power micro relays. Trailer lighting is powered by separate "main power wire" with it's own fuse and connected directly to the battery. Something like that I will install in my Tacoma when I get it prepared for towing again.

 

What seems to go bad with mine was the box part, where five wires go in and 4 come out. When mine went bad, I bought a generic box (not plug and play, and spliced on the plugs from the Curt harness. It was a much cheaper option, as I recall.

 

I did the same thing, only I got the generic one from Hopkins that worked with LED lights (on my trailer) and cut/joined it to the clips. This one also had a separate "power" wire that ran to the battery and I added an in-line fuse.

 

Thanks all, for the suggestions.

I went ahead and opened up the wiring loom under the bed, right behind the license plate, probed the five wires and found the following that I'll offer for those that may wonder down the line:

ground: white with black stripe
running lights: green
brake lights: green with white stripe
right turn: green with yellow stripe
backup: red

Thanks again.

 

also keep in mind per regulations every trailer needs lights with all functions: run, stop, turn

regardless of size and whether the truck is visible or not

https://www.etrailer.com/faq-trailer-lighting-info-and-regulations.aspx

 

Those 4 pin plugs are a pain I only install 7 pin plugs no problems