DIY easy $10 trailer lights plugin fix

DIY easy $10 trailer lights plugin fix

I decided to do this because I needed to fix my trailer lights but the damn things cost $40 and im on a very tight budget (fixed income) so I cut my non working module open to see whats in it that it has to cost so much.

low and behold there is nothing to it but there is a huge design flaw with it.

they run the wiring through a transistor which isn't needed but they often fail which is the only reason these things stop working, ever.

the core of how they work is the four diodes in them so the diodes do all the work and the transistors are just there like a fuse that can go bad.

so if you want to wire up trailer lights without buying the $40 contraption you can just follow these instructions but I prefer to think of this as a fix for one you already have wired in that failed on you.

I don't like tapping into stock wiring by cutting it which is what you would need to do if you never had trailer wiring before so I would say this is a fix that is a more recommended thing to be doing after you already bought your $40 trailer light that comes with the stock plugs so you dont cut and wires and then when it fails on you as they often do, then do this fix and you will never have it fail again. but if you don't mind splicing into your trucks stock wiring, then there is no reason not to do it as your first trailer wiring setup but you will need to buy the wires and trailer plug connector as well.

you just need a soldering iron, solder, heat shrink tubing, and electrical tape, then go buy 4 of these diodes or some like it: http://www.radioshack.com/product/index.jsp?productId=12673864

now how it works:

diodes allow electricity to go in only one direction and on our trucks the brakes have a separate wire then the flashers do, on many trucks the flashers are used as the brakes so those can be wired directly to the trailer plugs but on ours if you did this then every time you used either flasher then every light would flash like hazard lights and you would have no directional control. to solve this they use diodes to stop electricity from going to the other lights you don't want it to go to. simply cut the wires off of both sides of the module and connect the white and brown wires together, then solder in the diodes to the other wires as shown in the diagram.

in the diagram below you see how this works:

http://s1076.photobucket.com/user/keakar63/media/toyotatrailerlightmodulefix.jpg.html?sort=6&o=3

you can see how incredibly simple these things are but they are made with bad solder connections and have transistors in then that go bad all the time and the transistors aren't even doing anything except making these things quit working. when one fails there is nothing wrong with the diodes its the transistor or the solder connections went bad.

the power for the brakes goes through both middle diodes and sends power to both left and right flashers. when you need the driver flasher it goes through just the yellow wire and to the yellow flasher but the middle diode is also connected to it but the diode wont allow current to pass in the opposite direction so it acts like there is no connection there. the same happens on the opposite side for the passenger flasher.

this setup is indestructible and there are no moving parts or anything to wear out so unless you physicly crush the diodes they never fail.

this is a $10 repair to an otherwise $40 replacement harness for trailer lights and this setup will NEVER FAIL AGAIN.

this is also a $10 trailer wiring diagram so you don't have to buy one in the first place but for me, and I suggest the best thing to do, is just buy one for the very first time you connect trailer wires to your truck. I don't think you should ever cut and splice stock wiring even though people have done it that way for years and years.


NOTE: this was done for my Toyota but can work on other vehicles as well if your connector is wired with an extra wire other then the yellow, green, white, and brown. having the extra wire is what makes it necessary to use the diodes to prevent back feed of power to the other lights.

 

Hey There,

Appreciate the tutorial and budget fix! This seems like the ideal solution for my situation. My trailer harness control box is fried and the wiring seems to be hard wired into the rear left signal, so I don't think it's as simple as swapping in a new plug and play module, it'd have to do a little wire splicing in the tail light connectors. Plus I'm cheap, I want to fix what I have instead of buying a new harness every couple years.

Looking at your wiring diagram it seems simple enough, but at the moment I am feeling a bit thick. Cut out the module, check. Browns and whites just wire together, got that. Now it seems like I need to turn the red wire (truck side) and green/yellow wires (trailer side) from single to double leads so they can make the necessary connections to the diodes. Wondering if you had any photos of your wiring. Just curious the best way to make those Y adapters.

Thanks.

 

I am bringing this from the grave as I tried this method with my recent non-working harness.

unfortunately this method does not work properly and I advise against it. here's why.

the diode setup is correct for not allowing the current to flow back through either turn or brake light.

however, the resistor plays a major part in the equation. it prevents the brake signal from interfering with the turn signal.

the way the diagram is, the brake signal is a "constant" which means the light stays on all the time when you are slowing or stopped.

this prevents the "flashing" of the turn signal, which is required to indicate you are turning.

@keakar I thank you for the post and the cheap parts find (mine was $15 total) but there is a piece missing in the equation that needs researched further.

I'll have to crack open my old box and see how it's wired.

more to come.