Trailer Wiring and Groud Issues

[Rebel_Horseman]

Went to hook up to my buddy's Exxis 3-horse this weekend. Plugged the trailer into my bed plug and go to check the lights. Finally get the running lights to come on but when I hit the brakes the running lights go off and nothing else happens. The brake controller won't light up when the brake pedal is depress but when it's not depressed I get a constant green glow. Oh, my controller is a Tekonsha. Anyway, we check the wiring in the plug and all looks normal, and we crawl underneath and in the engine and check things out. All fuses are OK and we swapped the relays around and everything still works. I crawled back under it this evening and noticed a red wire in the nest under the back bumper that is not hooked up to anything. It's a large red wire that, when I removed the bed plug, goes to the center position of the plug. This is my ground wire I'm guessing. There's another red wire running to the plug on my bumper as well, so I'm guessing this is the same wire and it was never spliced. I need opinions. If I can't make anything out I'm thinking about bringing it to the trailer dealership up here and having them look at it.



Reb [><]

 

[ISBPilot]

Just my experience..........

I am assuming on a trailer that size, it is a gooseneck and has a 6-way round plug. If so, on my trailers that is a non used prong which I use as a hot wire or switch wire for accessories (load lights, interior lights, etc. ). It dos sound like a grounding problem, but through the hitch. Even though trailers are grounded through the plug, sometimes I have to pull up and wiggle them on the ball a little before all the lights work right. Give it a try before you rewire everything. Good luck.



Todd

 

[Rebel_Horseman]

Yep it's a gooseneck and there is the 6-way plug in the bed. I was also told that the trailer was grounded through the plug, so I didn't think pulling it a little would matter. When you mentioned the red wire being a hot wire it clicked. I remembered it was not the ground. If the hot line isn't hooked up, would that matter?



Reb [><]

 

[ISBPilot]

Nope, the center wire is an accessory wire. It has no effect on your signals and running lights when wired properly. Your ground should be white or black and wired to the one prong that is slightly larger than the others. On my work computer I have a picture of the proper wire diagram.



All of this depends on if the trailer is wired to the standard code or if it has been rewired or changed to match a truck that was wired improperly.



Keep us updated with what you find and will help if possible. Good luck.



Todd

 

[Rebel_Horseman]

10-4



I have an appointment with a trailer company Tuesday to get it looked at. Will post the results.



Reb [><]

 

[Loren]

Reb,



Here is some data on the truck plug wiring. You will have to draw a mirror image to apply this to the trailer, although the terminal numbers will be the same on both plugs.



You can check individual circuits by using a 12 volt battery. Connect the ground (negative terminal) to the ground wire and/or the trailer frame. Then, using a jumper wire, connect the positive terminal of the battery to the circuit you want to test. This should allow you to isolate where the problem is, and may save you a trip to the dealer.



Good luck,

Loren



P. S. I know this table isn't formatted as well as it should be, but it's taken me about half an hour to get this much. It's very difficult to build or insert a table into these replies.



P. P. S. I bought that book you mentioned in your P. M. I haven't started it yet.



**********

Trailer wiring codes:

Terminal  Recommended

 number  Wire  Gauge Circuit



1	White	10	Common ground

2	Blue	12	Electric brakes

3	Green	14	Tail, license, running lights

4	Black	10	Battery charge (hot)

5	Red	14	Left turn

6	Brown	14	Right turn

7	Yellow	14	Extra auxiliary (back up lights)

Looking at the receptacle on the truck, at the top is the keyway for the plug. There are three terminals to the right side and three to the left. The layout makes no sense but these are the pins:



Upper right: #4 (black wire): Battery charge: This pin should always have battery voltage = 12. 6 volts.



Middle right: #6 (brown wire): Right turn: This pin should have zero voltage with the lights off. It should read battery voltage intermittently when the right turn signal is flashing. It should have battery voltage continuously when the brakes are applied. My truck reads 11. 7 volts when this is powered.



Lower right: #2 (blue wire): Electric brakes: This pin’s voltage will vary with increased output from the brake controller. The Tekonsha Sentinel controller sends 0. 5 volts to this pin continuously. Voltage increases to battery voltage with full brake application.



Upper left: #3 (green wire): Tail and running lights: This pin should have zero volts when the lights are off, and battery voltage when the lights are on. Mine reads 0. 1 volt with the lights off. Not checked with the lights on.



Middle left: #5 (red wire): Left turn: Same as for #6, except for left turn signal.



Lower left: #1 (white wire): Ground: Should never have any voltage.



Center: #7 (yellow wire): Auxiliary pin: The travel trailer industry uses this pin as power to the backup lights. Dodge wires the factory receptacle that way. It should have zero volts when the backup lights are off and battery voltage when the truck is in reverse and the key is on, that is, whenever the truck’s backup lights are on. My truck reads zero with the lights off. Not checked with lights on.

 

[ropinfool2]

Just so you all know, different trailer manufacturers will swap the hot wire and the brake wire to give them a custom plug. I worked at a trailer dealership that carried two horse trailer brands and they were wired different from each other. Good luck. John

 

[Rebel_Horseman]

Took the truck to the local trailer dealer here that installed the hitch when the old owners bought the truck. They hooked up their machine and everything worked right! Guessing my buddy's trailer has his wiring a little bit different. Going to try it on my trailers this weekend to confirm.



Brian [><]

 

[ropinfool2]

Since you have a 6 way socket in the bed, open the cover, look at the male prongs and you will notice they are actually two pieces. Take a very small screwdriver, knife point, something and carefully spread them apart. Try not to touch any other prongs or the housing as you can short things out. Then go to the auto parts store and buy some dielectric grease and put a little in each of the holes of the plug (trailer end). This has fixed many problems. You didn't mention if the turn signals worked or not, they are the same wiring as the brakes, meaning the left turn (yellow wire) is the same wire as the left brake light and the right turn (green wire) is the same as the right brake light. Brown will be the running lights, ground is normally white, brakes are normally blue and hot is either black or red. Good luck to you. If you have any questions feel free to email me. John

 

[bnelson]

Gotta be the ground

1) Go to the Tekonsha web site and download a wiring diagram. If I remember right, it will be under the installation section. This will show you how the different plugs are wired. I was impressed with their site!



2) Any time the trailer lights are doing weird things, first try hooking a jumper wire from the tow vehicle to the trailer. The will establish a ground between the two units, and if the lights start working right, then you have an open circuit in a ground wire on one or the other. In theory, the hitch should carry the grounding current from the tow vehicle to the trailer, but the crud on the ball and receiver can easily prevent this from happening. Many a trailer has been totally re-wired out of frustration when the only problem was a bad ground. (Ask me how I learned this!)