Bought a 2015 GMC crewcab for a toad

nevadanick wrote:
Thank You very much. I am certainly capable of the work but the diode thing is something i know nothing of and i am not afraid to say when i dont know. Are diodes a certain size or value ? And are they directional ? what would i buy and where for diodes ? I appreciate the help you are giving me.

Nevadanick,
For all practical purposes and, in reality, a diode is a ONE WAY VALVE for electricity. Electricity can travel one way in a wire with a diode, but not the other direction. So, for an example. You "T" into your left turn/brake light wire of your new GMC, just before it enters the tail light housing, maybe a few inches away. Now, you hook up to your coach and, apply the left turn signal in the coach.

The electrical signal being sent from the turn signal handle on the steering column travels through the coach, through the umbilical and, enters that "T" you just did. For simpler analogy, I'll call it an intersection. That signal, hits that intersection and, it can turn right and, enter the tail light and function as requested.

But, because it hit an intersection of wiring, electricity CAN go both ways, right AND left. So, it turns left too. But, as soon as it hits that diode you installed, it cannot go any further. And, to answer another part of your questions, YES they are directional. When installed, you have to install them so they are facing the correct way.

Because, when you're driving your new GMC, and apply the left turn signal, that electricity travels down the wiring from the steering column through the wiring and, because you installed the diode correctly, it will travel right THROUGH that diode and, into the left tail light and function as normal.

So, that's how all that works. Now, where to purchase them. Well, normally I'd advise you to run down to your local Radio Shack and, pick up what you need. But, in recent months, Radio Shack has announced it will be closing the remainder of it's stores, permanently. I don't know where you're located so, you may or, may not have any still open near you. Most likely not.

Now, you can also buy them on line from ebay or, Amazon all day long. Amazon has a 20 pack of 10 amp ones for about $5.00 or so and a couple dollars shipping. You won't need that many but, it never hurts to have a couple extras JUST IN CASE one goes bad or, you screw one up during installation.

And, speaking of installation. A diode has "Band" painted all the way around the negative end. Usually, it's a black diode with a silver band. The way it's installed is, the band is the "Stop sign". So, you'd install it in your GMCs wiring in such a manner that, it will STOP the signal from the coach, from traveling forward to the rest of the GMC. In other words, the band end, will be closest to the tail light.

If you look at the diode icons in my diagram, you'll see an arrow and a line. The arrow indicates the direction normal flow of electricity. While the line, represents the band, and, it will block electricity from entering the diode and traveling the wrong way.

Now, as I stated before, I'm not a big fan of spending 5 times the amount needed for this little project but, you can also purchase a "Diode kit" from RV supplies houses like Camping World or, any other local Hitch sales/Trailer supplies etc. Those are normally around $25.00 for a two-pack. They're self explanatory in installation instructions. They are also equipped with female spade connectors so, no soldering is needed or done. Your choice on that one.

A diode is a diode. If you pay $1.50 or, $25.00, you're still installing the same thing. If you're capable of doing a little wire stripping and, some neat little soldering, the $1.50 way makes quite a bit more sense, excuse the pun. Hope this answers your questions.
Scott