Back-up lights and trailer running lights

You will need to follow the wires back to see if there is a break in the wire.

If the trailer brakes don't come on when you depress the brake pedal, the larger red wire to the back has lost connection. Red to brakes, brown to running lights, green to right turn and brake light, yellow to left turn and brake light. White is always the ground and BE REAL SURE the ground connections are REAL clean and REAL tight at ALL points because with out ground, nothing will work. Including the brakes.

suggest downloading the trailer pin standard for whatever number of pins your trailer plug has and tracing the wiring from the colors . The standard will tell you what color goes to what light and what pin number it should be on . Also 5 pin and 7 pin are different . You can plug a 5 pin into a 7 pin but the wiring is different .

Also check the trailer socket is grounded at the car body properly. As this can cause lots of weird symptoms.

Disconnect the trailer wiring and recheck the vehicle lighting. If it returns to normal, then obviously the trailer is the problem. Quite often the trailer plug loses its independent ground and it will back feed thru other circuits trying to locate one. Especially if its a boat trailer, water intrusion can cause havoc on the grounds due to corrosion. The under hood electrical center has circuits intentionally meant to be used for trailers. You CANNOT just jumper into the rear lights of the truck (tail, signals and brakes coming from the tail light connector). Because it uses a multi-function switch, the brakes and signals are actually the same circuit, and have to be wired separately for a trailer plug to operate.

You will need at least a 6way car and trailer connection.Start by clipping the plug ends off of your current system and rewire them to the plug Right turn, left turn, running lights, trailer brakes, ground, and then remove one of your trucks taillight assemblies and splice a wire to the reverse light. Then run it through the bumper to the final remaining wire on your 6way. On the trailer end run continuity test through the plug to ensure that the correct functions are going to the correct locations on the trailer. Install your reverse lights on the trailer and run them to the same pin location you spliced the reverse wire to earlier.

Check the bulbs in the trailer. If you know someone with a trailer that you could hook up to try that too. A large majority of trailer lighting systems use a simple circuit pattern. Like Christmas lights. . . one goes out they all go out. etc. Some boat trailer lights will burn out if they are hooked up when it's backed into the water. The pain of trailer stuff is figuring out if its really the trailer or not. When the cover is off the lights make sure you take a good look at the guts of the light. The brass pathways will actually arc and melt. Ruining the light. If its not the trailer start checking the vehicle connections. Remember not to overthink things and start with simple stuff first. Oh and recruit a helper to push the brakes and run back and forth it will speed things up greatly.

try http://www.etrailer.com/faq-wiring.aspx. This should help. The 5th wire is a lockout for the brakes that hooks to your back up lights. So when you back up, the brakes won't engauge. Typically white is ground, yellow is left turn, green is right turn, and brown is running lights.

You may have a bad ground or the truck or trailer may be wired differently. Get a test light and check your connections and make sure they all match . It is helpful to have someone work the directionals and brakes while testing. It saves you alot of running back and forth. Hope this helps John

The truck is protecting itself from the load impose by the trailer.. Chk the plug on the truck for wire gauge size. Turn any electrical loads off on the trailer, any and all. If fuse still blows then the fuse is either underated or the trailer has a dead short. In fact turn trail main power panel of. All lights work you say. So ck the inverter for defect byturning off the inverter on one of the trailers.

Hey Paul, it's most likely a wiring problem. There is one wire designated for just the running lights. What type of plug does the truck have? Probably 6 or 7 way (6 or 7 wire). You can check the plug-in at the truck with a multi-meter to see if there's power at that point. If there is, then the problem is somewhere from the trailer plug to the lights on the trailer. If you have a 7 way plug, the center plug is for aux. power (back up lights on what you pull, if equipped). One wire is power to the camper battery for a breakaway switch, one for left turn and stop, one for right turn and stop, a ground wire, one for running lights, and one for trailer brakes. To determine what wire does what, 1st with meter check volts of all wires w/ truck and trailer hooked up, truck running, power wire to battery for breakaway should show voltage if equipped w/ a trickle charge, brake wire will show low voltage, approx. 2 volts, apply brakes and should go up to approx. 12 volts, put on L turn signal, meter should go up and down, as power to blinker pulses on and off, do the same to determine which is the R turn signal (put foot on truck brakes will show voltage to brake lights AND brakes, continue w/ process of elimination to determine which is running lights, and exactly where power is not going.